Accuracy and reliability of different cone beam computed tomography (CBCT) devices for structural analysis of alveolar bone in comparison with multislice CT and micro-CT.

Science.gov (United States)

Van Dessel, Jeroen; Nicolielo, Laura Ferreira Pinheiro; Huang, Yan; Coudyzer, Walter; Salmon, Benjamin; Lambrichts, Ivo; Jacobs, Reinhilde

The aim of this study was to assess whether cone beam computed tomography (CBCT) may be used for clinically reliable alveolar bone quality assessment in comparison to its clinical alternatives, multislice computed tomography and the gold standard (micro-CT). Six dentate mandibular bone samples were scanned with seven CBCT devices (ProMax 3D Max, NewTom GiANO, Cranex 3D, 3D Accuitomo 170, Carestream 9300, Scanora 3D, I-CAT Next generation), one micro-CT scanner (SkyScan 1174) and one MSCT machine (Somatom Definition Flash) using two protocols (standard and high-resolution). MSCT and CBCT images were automatically spatially aligned on the micro-CT scan of the corresponding sample. A volume of interest was manually delineated on the micro-CT image and overlaid on the other scanning devices. Alveolar bone structures were automatically extracted using the adaptive thresholding algorithm. Based on the resulting binary images, an automatic 3D morphometric quantification was performed in a CT-Analyser (Bruker, Kontich, Belgium). The reliability and measurement errors were calculated for each modality compared to the gold standard micro-CT. Both MSCT and CBCT were associated with a clinically and statistically (P max, bone surface density -0.47 mm-1 min to 0.16 mm-1 max and trabecular thickness 0.15 mm min to 0.31 mm max) were significantly (P max and fractal dimension 0.08 min to 0.17 max) in all scanners compared to micro-CT. However, the structural pattern of the alveolar bone remained similar compared to that of the micro-CT for the ProMax 3D Max, NewTom GiANO, Cranex 3D, 3D Accuitomo 170 and Carestream 9300. On the other hand, the Scanora 3D, i-CAT Next Generation, standard and high-resolution MSCT displayed an overrated bone quantity and aberrant structural pattern compared to other scanning devices. The calculation of morphometric indices had an overall high reliability (intraclass correlation coefficient [ICC] 0.62 min to 0.99 max), except

Towards an inline reconstruction architecture for micro-CT systems

International Nuclear Information System (INIS)

Brasse, David; Humbert, Bernard; Mathelin, Carole; Rio, Marie-Christine; Guyonnet, Jean-Louis

2005-01-01

Recent developments in micro-CT have revolutionized the ability to examine in vivo living experimental animal models such as mouse with a spatial resolution less than 50 μm. The main requirements of in vivo imaging for biological researchers are a good spatial resolution, a low dose induced to the animal during the full examination and a reduced acquisition and reconstruction time for screening purposes. We introduce inline acquisition and reconstruction architecture to obtain in real time the 3D attenuation map of the animal fulfilling the three previous requirements. The micro-CT system is based on commercially available x-ray detector and micro-focus x-ray source. The reconstruction architecture is based on a cluster of PCs where a dedicated communication scheme combining serial and parallel treatments is implemented. In order to obtain high performance transmission rate between the detector and the reconstruction architecture, a dedicated data acquisition system is also developed. With the proposed solution, the time required to filter and backproject a projection of 2048 x 2048 pixels inside a volume of 140 mega voxels using the Feldkamp algorithm is similar to 500 ms, the time needed to acquire the same projection

Cone Beam CT vs. Fan Beam CT: A Comparison of Image Quality and Dose Delivered Between Two Differing CT Imaging Modalities.

Science.gov (United States)

Lechuga, Lawrence; Weidlich, Georg A

2016-09-12

A comparison of image quality and dose delivered between two differing computed tomography (CT) imaging modalities-fan beam and cone beam-was performed. A literature review of quantitative analyses for various image quality aspects such as uniformity, signal-to-noise ratio, artifact presence, spatial resolution, modulation transfer function (MTF), and low contrast resolution was generated. With these aspects quantified, cone beam computed tomography (CBCT) shows a superior spatial resolution to that of fan beam, while fan beam shows a greater ability to produce clear and anatomically correct images with better soft tissue differentiation. The results indicate that fan beam CT produces superior images to that of on-board imaging (OBI) cone beam CT systems, while providing a considerably less dose to the patient.

Processing of microCT implant-bone systems images using Fuzzy Mathematical Morphology

International Nuclear Information System (INIS)

Bouchet, A; Pastore, J; Colabella, L; Omar, S; Ballarre, J

2016-01-01

The relationship between a metallic implant and the existing bone in a surgical permanent prosthesis is of great importance since the fixation and osseointegration of the system leads to the failure or success of the surgery. Micro Computed Tomography is a technique that helps to visualize the structure of the bone. In this study, the microCT is used to analyze implant-bone systems images. However, one of the problems presented in the reconstruction of these images is the effect of the iron based implants, with a halo or fluorescence scattering distorting the micro CT image and leading to bad 3D reconstructions. In this work we introduce an automatic method for eliminate the effect of AISI 316L iron materials in the implant-bone system based on the application of Compensatory Fuzzy Mathematical Morphology for future investigate about the structural and mechanical properties of bone and cancellous materials. (paper)

Bone quality evaluation at dental implant site using multislice CT, micro-CT, and cone beam CT

NARCIS (Netherlands)

Parsa, A.; Ibrahim, N.; Hassan, B.; van der Stelt, P.; Wismeijer, D.

2015-01-01

Objectives The first purpose of this study was to analyze the correlation between bone volume fraction (BV/TV) and calibrated radiographic bone density Hounsfield units (HU) in human jaws, derived from micro-CT and multislice computed tomography (MSCT), respectively. The second aim was to assess the

MicroCT Bone Densitometry: Context Sensitivity, Beam Hardening Correction and the Effect of Surrounding Media

Directory of Open Access Journals (Sweden)

Philip L. Salmon

2014-12-01

Full Text Available The context-sensitivity of microCT bone densitometry due to beam hardening artefacts was assessed. Bones and teeth are scanned with varying thickness of surrounding media (water, alcohol, biological tissue and it is important to understand how this affects reconstructed attenuation (“density” of the mineralized tissue. Aluminium tubes and rods with thickness 0.127mm–5mm were scanned both in air or surrounded by up to 2cm of water. Scans were performed with different energy filters and degrees of software beam hardening correction (BHC. Also tested were the effects of signal-to-noise ratio, magnification and truncation. The thickness of an aluminium tube significantly affected its mean reconstructed attenuation. This effect of thickness could be reduced substantially by BHC for scans in air, but not for scans in water. Varying thickness of surrounding water also changed the mean attenuation of an aluminium tube. This artefact could be almost eliminated by an optimal BHC value. The “cupping” artefact of heterogeneous attenuation (elevated at outer surfaces could be corrected if aluminium was scanned in air, but in water BHC was much less effective. Scan truncation, changes to magnification and signal-to-noise ratio also caused artificial changes to measured attenuation. Measurement of bone mineral density by microCT is highly context sensitive. A surrounding layer of liquid or biological tissue reduces the ability of software BHC to remove bone density artefacts. Sample thickness, truncation, magnification and signal to noise ratio also affect reconstructed attenuation. Thus it is important for densitometry that sample and calibration phantom dimensions and mounting materials are standardised.

Advanced single-slice rebinning for tilted spiral cone-beam CT

International Nuclear Information System (INIS)

Kachelriess, Marc; Fuchs, Theo; Schaller, Stefan; Kalender, Willi A.

2001-01-01

Future medical CT scanners and today's micro CT scanners demand cone-beam reconstruction algorithms that are capable of reconstructing data acquired from a tilted spiral trajectory where the vector of rotation is not necessarily parallel to the vector of table increment. For the medical CT scanner this case of nonparallel object motion is met for nonzero gantry tilt: the table moves into a direction that is not perpendicular to the plane of rotation. Since this is not a special application of medical CT but rather a daily routine in head exams, there is a strong need for corresponding reconstruction algorithms. In contrast to medical CT, where the special case of nonperpendicular motion is used on purpose, micro CT scanners cannot avoid aberrations of the rotational axis and the table increment vector due to alignment problems. Especially for those micro CT scanners that have the lifting stage mounted on the rotation table (in contrast to setups where the lifting stage holds the rotation table), this kind of misalignment is equivalent to a gantry tilt. We therefore generalize the advanced single-slice rebinning algorithm (ASSR), which is considered a very promising approach for medical cone-beam reconstruction due to its high image quality and its high reconstruction speed [Med. Phys. 27, 754-772 (2000)], to the case of tilted gantries. We evaluate this extended ASSR approach (which we will denote as ASSR + , for convenience) in comparison to the original ASSR algorithm using simulated phantom data for reconstruction. For the case of nonparallel object motion ASSR + shows significant improvements over ASSR, however, its computational complexity is slightly increased due to the broken symmetry of the spiral trajectory

The reliability of cone-beam computed tomography to assess bone density at dental implant recipient sites: a histomorphometric analysis by micro-CT.

Science.gov (United States)

González-García, Raúl; Monje, Florencio

2013-08-01

The aim of this study was to objectively assess the reliability of the cone-beam computed tomography (CBCT) as a tool to pre-operatively determine radiographic bone density (RBD) by the density values provided by the system, analyzing its relationship with histomorphometric bone density expressed as bone volumetric fraction (BV/TV) assessed by micro-CT of bone biopsies at the site of insertion of dental implants in the maxillary bones. Thirty-nine bone biopsies of the maxillary bones at the sites of 39 dental implants from 31 edentulous healthy patients were analyzed. The NobelGuide™ software was used for implant planning, which also allowed fabrication of individual stereolithographic surgical guides. The analysis of CBCT images allowed pre-operative determination of mean density values of implant recipient sites along the major axis of the planned implants (axial RBD). Stereolithographic surgical guides were used to guide implant insertion and also to extract cylindrical bone biopsies from the core of the exact implant site. Further analysis of several osseous micro-structural variables including BV/TV was performed by micro-CT of the extracted bone biopsies. Mean axial RBD was 478 ± 212 (range: 144-953). A statistically significant difference (P = 0.02) was observed among density values of the cortical bone of the upper maxilla and mandible. A high positive Pearson's correlation coefficient (r = 0.858, P micro-CT at the site of dental implants in the maxillary bones. Pre-operative estimation of density values by CBCT is a reliable tool to objectively determine bone density. © 2012 John Wiley & Sons A/S.

Detecting metastasis of gastric carcinoma using high-resolution micro-CT system: in vivo small animal study

Science.gov (United States)

Liu, Junting; Tian, Jie; Liang, Jimin; Li, Xiangsi; Yang, Xiang; Chen, Xiaofeng; Chen, Yi; Zhou, Yuanfang; Wang, Xiaorui

2011-03-01

Immunocytochemical and immunofluorescence staining are used for identifying the characteristics of metastasis in traditional ways. Micro-computed tomography (micro-CT) is a useful tool for monitoring and longitudinal imaging of tumor in small animal in vivo. In present study, we evaluated the feasibility of the detection for metastasis of gastric carcinoma by high-resolution micro-CT system with omnipaque accumulative enhancement method in the organs. Firstly, a high-resolution micro-CT ZKKS-MCT-sharp micro-CT was developed by our research group and Guangzhou Zhongke Kaisheng Medical Technology Co., Ltd. Secondly, several gastric carcinoma models were established through inoculating 2x106 BGC-823 gastric carcinoma cells subcutaneously. Thirdly, micro-CT scanning was performed after accumulative enhancement method of intraperitoneal injection of omnipaque contrast agent containing 360 mg iodine with a concentration of 350 mg I/ml. Finally, we obtained high-resolution anatomical information of the metastasis in vivo in a BALB/c NuNu nude mouse, the 3D tumor architecture is revealed in exquisite detail at about 35 μm spatial resolution. In addition, the accurate shape and volume of the micrometastasis as small as 0.78 mm3 can be calculated with our software. Overall, our data suggest that this imaging approach and system could be used to enhance the understanding of tumor proliferation, metastasis and could be the basis for evaluating anti-tumor therapies.

Cardiac cone-beam CT

International Nuclear Information System (INIS)

Manzke, Robert

2005-01-01

This doctoral thesis addresses imaging of the heart with retrospectively gated helical cone-beam computed tomography (CT). A thorough review of the CT reconstruction literature is presented in combination with a historic overview of cardiac CT imaging and a brief introduction to other cardiac imaging modalities. The thesis includes a comprehensive chapter about the theory of CT reconstruction, familiarizing the reader with the problem of cone-beam reconstruction. The anatomic and dynamic properties of the heart are outlined and techniques to derive the gating information are reviewed. With the extended cardiac reconstruction (ECR) framework, a new approach is presented for the heart-rate-adaptive gated helical cardiac cone-beam CT reconstruction. Reconstruction assessment criteria such as the temporal resolution, the homogeneity in terms of the cardiac phase, and the smoothness at cycle-to-cycle transitions are developed. Several reconstruction optimization approaches are described: An approach for the heart-rate-adaptive optimization of the temporal resolution is presented. Streak artifacts at cycle-to-cycle transitions can be minimized by using an improved cardiac weighting scheme. The optimal quiescent cardiac phase for the reconstruction can be determined automatically with the motion map technique. Results for all optimization procedures applied to ECR are presented and discussed based on patient and phantom data. The ECR algorithm is analyzed for larger detector arrays of future cone-beam systems throughout an extensive simulation study based on a four-dimensional cardiac CT phantom. The results of the scientific work are summarized and an outlook proposing future directions is given. The presented thesis is available for public download at www.cardiac-ct.net

[Accurate 3D free-form registration between fan-beam CT and cone-beam CT].

Science.gov (United States)

Liang, Yueqiang; Xu, Hongbing; Li, Baosheng; Li, Hongsheng; Yang, Fujun

2012-06-01

Because the X-ray scatters, the CT numbers in cone-beam CT cannot exactly correspond to the electron densities. This, therefore, results in registration error when the intensity-based registration algorithm is used to register planning fan-beam CT and cone-beam CT. In order to reduce the registration error, we have developed an accurate gradient-based registration algorithm. The gradient-based deformable registration problem is described as a minimization of energy functional. Through the calculus of variations and Gauss-Seidel finite difference method, we derived the iterative formula of the deformable registration. The algorithm was implemented by GPU through OpenCL framework, with which the registration time was greatly reduced. Our experimental results showed that the proposed gradient-based registration algorithm could register more accurately the clinical cone-beam CT and fan-beam CT images compared with the intensity-based algorithm. The GPU-accelerated algorithm meets the real-time requirement in the online adaptive radiotherapy.

A study of effective sequences on micro-CT in the dent-maxillo-facial region

International Nuclear Information System (INIS)

Kato, Masataka; Mori, Shintaro; Sakayanagi, Masashi; Fujita, Yuzo; Kaneda, Takashi

2005-01-01

Microfocus computed tomography (micro-CT) using cone-beam scan is becoming widely used for various studies of oral structures. However, this machine has not been used to evaluate the effective parameters for two-dimensional (2D) or three-dimensional (3D) images. This study evaluated the effective parameters of micro-CT for 2D or 3D images of oral hard tissue structures. We evaluated the CT value of 5 human teeth (upper first molars) to determine suitable CT value examined according to several X-ray parameters using conformal radiotherapy (CRT) on a work station. CT information from the specimens was obtained using a micro-CT (Toscaner-31300 μ, Toshiba ITC), under the conditions of tube voltage of 75 kV, tube current of 120 μA, 100∼1600 views, the number of times of addition, 512 x 512 pixel matrix, and 0.2 slice thickness. We made 3D-reconstruction images from the micro-CT data. Three-dimensional reconstruction was performed using 2D images processed by the volume-rendering method using 3D-reconstruction software (TRI/3D BON, RATOC system engineering). Then, we evaluate the 3D tooth images. In the assessment of images, three dental radiologists evaluated several 3D tooth images using 3D-reconstruction images. Each image was scored on a five-level scale by Scheffe one-pair comparison method as follows: 5: much easier to evaluate, 4: easier to evaluate, 3: equivalent, 2: harder to evaluate, 1: much harder to evaluate. In scoring, each of the three dental radiologists made an individual assessment, and when differences among individual scores occurred, the score was ultimately assigned by consensus among the three individuals. Statistical analysis of the scores assigned by the three dental radiologists as described above was carried out using Stat View-J 5.0 (Abacus Concepts, Inc, USA) statistical software and Tukey-Kramer multiple-comparison testing. The optimal CT value for evaluating the human tooth by micro-CT is 600 on 2D images. On 3D images, the optimal

Performance evaluation of the General Electric eXplore CT 120 micro-CT using the vmCT phantom

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Bahri, M.A., E-mail: M.Bahri@ulg.ac.be [ULg-Liege University, Cyclotron Research Centre, Liege, Bat. 30, Allee du 6 aout, 8 (Belgium); Warnock, G.; Plenevaux, A. [ULg-Liege University, Cyclotron Research Centre, Liege, Bat. 30, Allee du 6 aout, 8 (Belgium); Choquet, P.; Constantinesco, A. [Biophysique et Medecine Nucleaire, Hopitaux universitaires de Strasbourg, Strasbourg (France); Salmon, E.; Luxen, A. [ULg-Liege University, Cyclotron Research Centre, Liege, Bat. 30, Allee du 6 aout, 8 (Belgium); Seret, A. [ULg-Liege University, Cyclotron Research Centre, Liege, Bat. 30, Allee du 6 aout, 8 (Belgium); ULg-Liege University, Experimental Medical Imaging, Liege (Belgium)

2011-08-21

The eXplore CT 120 is the latest generation micro-CT from General Electric. It is equipped with a high-power tube and a flat-panel detector. It allows high resolution and high contrast fast CT scanning of small animals. The aim of this study was to compare the performance of the eXplore CT 120 with that of the eXplore Ultra, its predecessor for which the methodology using the vmCT phantom has already been described . The phantom was imaged using typical a rat (fast scan or F) or mouse (in vivo bone scan or H) scanning protocols. With the slanted edge method, a 10% modulation transfer function (MTF) was observed at 4.4 (F) and 3.9-4.4 (H) mm{sup -1} corresponding to 114 {mu}m resolution. A fairly larger MTF was obtained by the coil method with the MTF for the thinnest coil (3.3 mm{sup -1}) equal to 0.32 (F) and 0.34 (H). The geometric accuracy was better than 0.3%. There was a highly linear (R{sup 2}>0.999) relationship between measured and expected CT numbers for both the CT number accuracy and linearity sections of the phantom. A cupping effect was clearly seen on the uniform slices and the uniformity-to-noise ratio ranged from 0.52 (F) to 0.89 (H). The air CT number depended on the amount of polycarbonate surrounding the area where it was measured; a difference as high as approximately 200 HU was observed. This hindered the calibration of this scanner in HU. This is likely due to the absence of corrections for beam hardening and scatter in the reconstruction software. However in view of the high linearity of the system, the implementation of these corrections would allow a good quality calibration of the scanner in HU. In conclusion, the eXplore CT 120 achieved a better spatial resolution than the eXplore Ultra (based on previously reported specifications) and future software developments will include beam hardening and scatter corrections that will make the new generation CT scanner even more promising.

Reduction of ring artefacts in high resolution micro-CT reconstructions

International Nuclear Information System (INIS)

Sijbers, Jan; Postnov, Andrei

2004-01-01

High resolution micro-CT images are often corrupted by ring artefacts, prohibiting quantitative analysis and hampering post processing. Removing or at least significantly reducing such artefacts is indispensable. However, since micro-CT systems are pushed to the extremes in the quest for the ultimate spatial resolution, ring artefacts can hardly be avoided. Moreover, as opposed to clinical CT systems, conventional correction schemes such as flat-field correction do not lead to satisfactory results. Therefore, in this note a simple but efficient and fast post processing method is proposed that effectively reduces ring artefacts in reconstructed μ-CT images. (note)

Micro CT based truth estimation of nodule volume

Science.gov (United States)

Kinnard, L. M.; Gavrielides, M. A.; Myers, K. J.; Zeng, R.; Whiting, B.; Lin-Gibson, S.; Petrick, N.

2010-03-01

With the advent of high-resolution CT, three-dimensional (3D) methods for nodule volumetry have been introduced, with the hope that such methods will be more accurate and consistent than currently used planar measures of size. However, the error associated with volume estimation methods still needs to be quantified. Volume estimation error is multi-faceted in the sense that there is variability associated with the patient, the software tool and the CT system. A primary goal of our current research efforts is to quantify the various sources of measurement error and, when possible, minimize their effects. In order to assess the bias of an estimate, the actual value, or "truth," must be known. In this work we investigate the reliability of micro CT to determine the "true" volume of synthetic nodules. The advantage of micro CT over other truthing methods is that it can provide both absolute volume and shape information in a single measurement. In the current study we compare micro CT volume truth to weight-density truth for spherical, elliptical, spiculated and lobulated nodules with diameters from 5 to 40 mm, and densities of -630 and +100 HU. The percent differences between micro CT and weight-density volume for -630 HU nodules range from [-21.7%, -0.6%] (mean= -11.9%) and the differences for +100 HU nodules range from [-0.9%, 3.0%] (mean=1.7%).

Study of effective dose of various protocols in equipment cone beam CT

International Nuclear Information System (INIS)

Soares, M. R.; Maia, A. F.; Batista, W. O.; Caldas, L. V. E.; Lara, P. A.

2014-08-01

Currently the cone beam computed tomography is widely used in various procedures of dental radiology. Although the doses values associated with the procedures of cone beam CT are low compared to typical values associated with dental radiology procedure in multi slices CT. However can be high compared to typical values of other techniques commonly used in dental radiology. The present scenario is a very wide range of designs of equipment and, consequently, lack of uniformity in all parameters associated with x-ray generation and geometry. In this context, this study aimed to evaluate and calculate the absorbed dose in organs and tissues relevant and estimate effective dose for different protocols with different geometries of exposure in five cone beam CT equipment. For this, a female Alderson anthropomorphic phantom, manufactured by Radiology Support Devices was used. The phantom was irradiated with 26 dosimeters LiF: Mg, Ti (TLD-100), inserted in organs and tissues along the layers forming the head and neck of the phantom. The equipment used, in this present assessment, was: i-CAT Classical, Kodak 9000 3D, Gendex GXCB 500, Sirona Orthophos X G 3D and Planmeca Pro Max 3D. The effective doses were be determined by the ICRP 103 weighting factors. The values were between 7.0 and 111.5 micro Sv, confirming the broad dose range expected due to the diversity of equipment and protocols used in each equipment. The values of effective dose per Fov size were: between 7 and 51.2 micro Sv for located Fov; between 17.6 and 52.0 micro Sv for medium Fov; and between 11.5 and 43.1 micro Sv to large Fov (maxillofacial). In obtaining the effective dose the measurements highlighted a relevance contribution of dose absorbed by the remaining organs (36%), Salivary glands (30%), thyroid (12%) and bone marrow (12%). (Author)

Study of effective dose of various protocols in equipment cone beam CT

Energy Technology Data Exchange (ETDEWEB)

Soares, M. R.; Maia, A. F. [Universidade Federale de Sergipe, Departamento de Fisica, Cidade Universitaria Prof. Jose Aloisio de Campos, Marechal Rondon s/n, Jardim Rosa Elze, 49-100000 Sao Cristovao, Sergipe (Brazil); Batista, W. O. [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Barbalho, Salvador, 40301015 Bahia (Brazil); Caldas, L. V. E.; Lara, P. A., E-mail: mrs2206@gmail.com [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)

2014-08-15

Currently the cone beam computed tomography is widely used in various procedures of dental radiology. Although the doses values associated with the procedures of cone beam CT are low compared to typical values associated with dental radiology procedure in multi slices CT. However can be high compared to typical values of other techniques commonly used in dental radiology. The present scenario is a very wide range of designs of equipment and, consequently, lack of uniformity in all parameters associated with x-ray generation and geometry. In this context, this study aimed to evaluate and calculate the absorbed dose in organs and tissues relevant and estimate effective dose for different protocols with different geometries of exposure in five cone beam CT equipment. For this, a female Alderson anthropomorphic phantom, manufactured by Radiology Support Devices was used. The phantom was irradiated with 26 dosimeters LiF: Mg, Ti (TLD-100), inserted in organs and tissues along the layers forming the head and neck of the phantom. The equipment used, in this present assessment, was: i-CAT Classical, Kodak 9000 3D, Gendex GXCB 500, Sirona Orthophos X G 3D and Planmeca Pro Max 3D. The effective doses were be determined by the ICRP 103 weighting factors. The values were between 7.0 and 111.5 micro Sv, confirming the broad dose range expected due to the diversity of equipment and protocols used in each equipment. The values of effective dose per Fov size were: between 7 and 51.2 micro Sv for located Fov; between 17.6 and 52.0 micro Sv for medium Fov; and between 11.5 and 43.1 micro Sv to large Fov (maxillofacial). In obtaining the effective dose the measurements highlighted a relevance contribution of dose absorbed by the remaining organs (36%), Salivary glands (30%), thyroid (12%) and bone marrow (12%). (Author)

A faster ordered-subset convex algorithm for iterative reconstruction in a rotation-free micro-CT system

International Nuclear Information System (INIS)

Quan, E; Lalush, D S

2009-01-01

We present a faster iterative reconstruction algorithm based on the ordered-subset convex (OSC) algorithm for transmission CT. The OSC algorithm was modified such that it calculates the normalization term before the iterative process in order to save computational cost. The modified version requires only one backprojection per iteration as compared to two required for the original OSC. We applied the modified OSC (MOSC) algorithm to a rotation-free micro-CT system that we proposed previously, observed its performance, and compared with the OSC algorithm for 3D cone-beam reconstruction. Measurements on the reconstructed images as well as the point spread functions show that MOSC is quite similar to OSC; in noise-resolution trade-off, MOSC is comparable with OSC in a regular-noise situation and it is slightly worse than OSC in an extremely high-noise situation. The timing record shows that MOSC saves 25-30% CPU time, depending on the number of iterations used. We conclude that the MOSC algorithm is more efficient than OSC and provides comparable images.

Characteristics and performance of a micro-MOSFET: An 'imageable' dosimeter for image-guided radiotherapy

International Nuclear Information System (INIS)

Rowbottom, Carl G.; Jaffray, David A.

2004-01-01

The performance and characteristics of a miniature metal oxide semiconductor field effect transistor (micro-MOSFET) detector was investigated for its potential application to integral system tests for image-guided radiotherapy. In particular, the position of peak response to a slit of radiation was determined for the three principal axes to define the co-ordinates for the center of the active volume of the detector. This was compared to the radiographically determined center of the micro-MOSFET visible using cone-beam CT. Additionally, the angular sensitivity of the micro-MOSFET was measured. The micro-MOSFETs are clearly visible on the cone-beam CT images, and produce no artifacts. The center of the active volume of the micro-MOSFET aligned with the center of the visible micro-MOSFET on the cone-beam CT images for the x and y axes to within 0.20 mm and 0.15 mm, respectively. In z, the long axis of the detector, the peak response was found to be 0.79 mm from the tip of the visible micro-MOSFET. Repeat experiments verified that the position of the peak response of the micro-MOSFET was reproducible. The micro-MOSFET response for 360 deg. of rotation in the axial plane to the micro-MOSFET was ±2%, consistent with values quoted by the manufacturer. The location of the active volume of the micro-MOSFETs under investigation can be determined from the centroid of the visible micro-MOSFET on cone-beam CT images. The CT centroid position corresponds closely to the center of the detector response to radiation. The ability to use the cone-beam CT to locate the active volume to within 0.20 mm allows their use in an integral system test for the imaging of and dose delivery to a phantom containing an array of micro-MOSFETs. The small angular sensitivity allows the investigation of noncoplanar beams

Scout-view assisted interior micro-CT

International Nuclear Information System (INIS)

Sharma, Kriti Sen; Narayanan, Shree; Agah, Masoud; Holzner, Christian; Vasilescu, Dragoş M; Jin, Xin; Hoffman, Eric A; Yu, Hengyong; Wang, Ge

2013-01-01

Micro computed tomography (micro-CT) is a widely-used imaging technique. A challenge of micro-CT is to quantitatively reconstruct a sample larger than the field-of-view (FOV) of the detector. This scenario is characterized by truncated projections and associated image artifacts. However, for such truncated scans, a low resolution scout scan with an increased FOV is frequently acquired so as to position the sample properly. This study shows that the otherwise discarded scout scans can provide sufficient additional information to uniquely and stably reconstruct the interior region of interest. Two interior reconstruction methods are designed to utilize the multi-resolution data without significant computational overhead. While most previous studies used numerically truncated global projections as interior data, this study uses truly hybrid scans where global and interior scans were carried out at different resolutions. Additionally, owing to the lack of standard interior micro-CT phantoms, we designed and fabricated novel interior micro-CT phantoms for this study to provide means of validation for our algorithms. Finally, two characteristic samples from separate studies were scanned to show the effect of our reconstructions. The presented methods show significant improvements over existing reconstruction algorithms. (paper)

In vivo microCT imaging of rodent cerebral vasculature

International Nuclear Information System (INIS)

Seo, Youngho; Hasegawa, Bruce H; Hashimoto, Tomoki; Nuki, Yoshitsugu

2008-01-01

Computed tomography (CT) remains a critical diagnostic tool for evaluating patients with cerebrovascular disease, and the advent of specialized systems for imaging rodents has extended these techniques to small animal models of these diseases. We therefore have evaluated in vivo methods of imaging rat models of hemorrhagic stroke using a high resolution compact computed tomography ('microCT') system (FLEX(tm) X-O(tm), Gamma Medica-Ideas, Northridge, CA). For all in vivo studies, the head of the anesthetized rat was secured in a custom immobilization device for microCT imaging with 512 projections over 2 min at 60 kVp and 0.530 mA (I tube x t/rotation = 63.6 mAs). First, imaging without iodinated contrast was performed (a) to differentiate the effect of contrast agent in contrast-enhanced CT and (b) to examine the effectiveness of the immobilization device between two time points of CT acquisitions. Then, contrast-enhanced CT was performed with continuous administration of iopromide (300 mgI ml -1 at 1.2 ml min -1 ) to visualize aneurysms and other vascular formations in the carotid and cerebral arteries that may precede subarachnoid hemorrhage. The accuracy of registration between the noncontrast and contrast-enhanced CT images with the immobilization device was compared against the images aligned with normalized mutual information using FMRIB's linear image registration tool (FLIRT). Translations and rotations were examined between the FLIRT-aligned noncontrast CT image and the nonaligned noncontrast CT image. These two data sets demonstrated translational and rotational differences of less than 0.5 voxel (∼85 μm) and 0.5 deg., respectively. Noncontrast CT demonstrated a very small volume (0.1 ml) of femoral arterial blood introduced surgically into the rodent brain. Continuous administration of iopromide during the CT acquisition produced consistent vascular contrast in the reconstructed CT images. As a result, carotid arteries and major cerebral blood vessels

In vivo microCT imaging of rodent cerebral vasculature

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Seo, Youngho; Hasegawa, Bruce H [Center for Molecular and Functional Imaging, Department of Radiology, University of California, San Francisco, CA 94143 (United States); Hashimoto, Tomoki; Nuki, Yoshitsugu [Center for Cerebrovascular Research, Department of Anesthesia and Perioperative Care, University of California, San Francisco, CA 94143 (United States)], E-mail: youngho.seo@radiology.ucsf.edu

2008-04-07

Computed tomography (CT) remains a critical diagnostic tool for evaluating patients with cerebrovascular disease, and the advent of specialized systems for imaging rodents has extended these techniques to small animal models of these diseases. We therefore have evaluated in vivo methods of imaging rat models of hemorrhagic stroke using a high resolution compact computed tomography ('microCT') system (FLEX(tm) X-O(tm), Gamma Medica-Ideas, Northridge, CA). For all in vivo studies, the head of the anesthetized rat was secured in a custom immobilization device for microCT imaging with 512 projections over 2 min at 60 kVp and 0.530 mA (I{sub tube} x t/rotation = 63.6 mAs). First, imaging without iodinated contrast was performed (a) to differentiate the effect of contrast agent in contrast-enhanced CT and (b) to examine the effectiveness of the immobilization device between two time points of CT acquisitions. Then, contrast-enhanced CT was performed with continuous administration of iopromide (300 mgI ml{sup -1} at 1.2 ml min{sup -1}) to visualize aneurysms and other vascular formations in the carotid and cerebral arteries that may precede subarachnoid hemorrhage. The accuracy of registration between the noncontrast and contrast-enhanced CT images with the immobilization device was compared against the images aligned with normalized mutual information using FMRIB's linear image registration tool (FLIRT). Translations and rotations were examined between the FLIRT-aligned noncontrast CT image and the nonaligned noncontrast CT image. These two data sets demonstrated translational and rotational differences of less than 0.5 voxel ({approx}85 {mu}m) and 0.5 deg., respectively. Noncontrast CT demonstrated a very small volume (0.1 ml) of femoral arterial blood introduced surgically into the rodent brain. Continuous administration of iopromide during the CT acquisition produced consistent vascular contrast in the reconstructed CT images. As a result, carotid

Feasibility of small animal cranial irradiation with the microRT system

International Nuclear Information System (INIS)

Kiehl, Erich L.; Stojadinovic, Strahinja; Malinowski, Kathleen T.; Limbrick, David; Jost, Sarah C.; Garbow, Joel R.; Rubin, Joshua B.; Deasy, Joseph O.; Khullar, Divya; Izaguirre, Enrique W.; Parikh, Parag J.; Low, Daniel A.; Hope, Andrew J.

2008-01-01

Purpose: To develop and validate methods for small-animal CNS radiotherapy using the microRT system. Materials and Methods: A custom head immobilizer was designed and built to integrate with a pre-existing microRT animal couch. The Delrin couch-immobilizer assembly, compatible with multiple imaging modalities (CT, microCT, microMR, microPET, microSPECT, optical), was first imaged via CT in order to verify the safety and reproducibility of the immobilization method. Once verified, the subject animals were CT-scanned while positioned within the couch-immobilizer assembly for treatment planning purposes. The resultant images were then imported into CERR, an in-house-developed research treatment planning system, and registered to the microRTP treatment planning space using rigid registration. The targeted brain was then contoured and conformal radiotherapy plans were constructed for two separate studies: (1) a whole-brain irradiation comprised of two lateral beams at the 90 degree sign and 270 degree sign microRT treatment positions and (2) a hemispheric (left-brain) irradiation comprised of a single A-P vertex beam at the 0 degree sign microRT treatment position. During treatment, subject animals (n=48) were positioned to the CERR-generated treatment coordinates using the three-axis microRT motor positioning system and were irradiated using a clinical Ir-192 high-dose-rate remote after-loading system. The radiation treatment course consisted of 5 Gy fractions, 3 days per week. 90% of the subjects received a total dose of 30 Gy and 10% received a dose of 60 Gy. Results: Image analysis verified the safety and reproducibility of the immobilizer. CT scans generated from repeated reloading and repositioning of the same subject animal in the couch-immobilizer assembly were fused to a baseline CT. The resultant analysis revealed a 0.09 mm average, center-of-mass translocation and negligible volumetric error in the contoured, murine brain. The experimental use of the head

Dual-energy attenuation coefficient decomposition with differential filtration and application to a microCT scanner

International Nuclear Information System (INIS)

Taschereau, R; Silverman, R W; Chatziioannou, A F

2010-01-01

Dual-energy x-ray computed tomography (DECT) has the capability to decompose attenuation coefficients using two basis functions and has proved its potential in reducing beam-hardening artifacts from reconstructed images. The method typically involves two successive scans with different x-ray tube voltage settings. This work proposes an approach to dual-energy imaging through x-ray beam filtration that requires only one scan and a single tube voltage setting. It has been implemented in a preclinical microCT tomograph with minor modifications. Retrofitting of the microCT scanner involved the addition of an automated filter wheel and modifications to the acquisition and reconstruction software. Results show that beam-hardening artifacts are reduced to noise level. Acquisition of a μ-Compton image is well suited for attenuation-correction of PET images while dynamic energy selection (4D viewing) offers flexibility in image viewing by adjusting contrast and noise levels to suit the task at hand. All dual-energy and single energy reference scans were acquired at the same soft tissue dose level of 50 mGy.

Dual-energy attenuation coefficient decomposition with differential filtration and application to a microCT scanner

Energy Technology Data Exchange (ETDEWEB)

Taschereau, R; Silverman, R W; Chatziioannou, A F [Crump Institute for Molecular Imaging, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States)], E-mail: rtaschereau@mednet.ucla.edu

2010-02-21

Dual-energy x-ray computed tomography (DECT) has the capability to decompose attenuation coefficients using two basis functions and has proved its potential in reducing beam-hardening artifacts from reconstructed images. The method typically involves two successive scans with different x-ray tube voltage settings. This work proposes an approach to dual-energy imaging through x-ray beam filtration that requires only one scan and a single tube voltage setting. It has been implemented in a preclinical microCT tomograph with minor modifications. Retrofitting of the microCT scanner involved the addition of an automated filter wheel and modifications to the acquisition and reconstruction software. Results show that beam-hardening artifacts are reduced to noise level. Acquisition of a {mu}-Compton image is well suited for attenuation-correction of PET images while dynamic energy selection (4D viewing) offers flexibility in image viewing by adjusting contrast and noise levels to suit the task at hand. All dual-energy and single energy reference scans were acquired at the same soft tissue dose level of 50 mGy.

Synchrotron x-ray studies of the keel of the short-spined sea urchin lytechinus variegatus: absorption microtomography (microCT) and small beam diffraction mapping

International Nuclear Information System (INIS)

Stock, S.R.; Barss, J.; Dahl, T.; Veis, A.; Almer, J.D.; De Carlo, F.

2003-01-01

In sea urchin teeth, the keel plays an important structural role, and this paper reports results of microstructural characterization of the keel of Lytechinus variegatus using two noninvasive synchrotron x-ray techniques: x-ray absorption microtomography (microCT) and x-ray diffraction mapping. MicroCT with 14 keV x-rays mapped the spatial distribution of mineral at the 1.3 microm level in a millimeter-sized fragment of a mature portion of the keel. Two rows of low absorption channels (i.e., primary channels) slightly less than 10 microm in diameter were found running linearly from the flange to the base of the keel and parallel to its sides. The primary channels paralleled the oral edge of the keel, and the microCT slices revealed a planar secondary channel leading from each primary channel to the side of the keel. The primary and secondary channels were more or less coplanar and may correspond to the soft tissue between plates of the carinar process. Transmission x-ray diffraction with 80.8 keV x-rays and a 0.1 mm beam mapped the distribution of calcite crystal orientations and the composition Ca(1-x)Mg(x)CO(3) of the calcite. Unlike the variable Mg concentration and highly curved prisms found in the keel of Paracentrotus lividus, a constant Mg content (x = 0.13) and relatively little prism curvature was found in the keel of Lytechinus variegatus.

Micro-CTvlab: A web based virtual gallery of biological specimens using X-ray microtomography (micro-CT).

Science.gov (United States)

Keklikoglou, Kleoniki; Faulwetter, Sarah; Chatzinikolaou, Eva; Michalakis, Nikitas; Filiopoulou, Irene; Minadakis, Nikos; Panteri, Emmanouela; Perantinos, George; Gougousis, Alexandros; Arvanitidis, Christos

2016-01-01

During recent years, X-ray microtomography (micro-CT) has seen an increasing use in biological research areas, such as functional morphology, taxonomy, evolutionary biology and developmental research. Micro-CT is a technology which uses X-rays to create sub-micron resolution images of external and internal features of specimens. These images can then be rendered in a three-dimensional space and used for qualitative and quantitative 3D analyses. However, the online exploration and dissemination of micro-CT datasets are rarely made available to the public due to their large size and a lack of dedicated online platforms for the interactive manipulation of 3D data. Here, the development of a virtual micro-CT laboratory (Micro-CT vlab ) is described, which can be used by everyone who is interested in digitisation methods and biological collections and aims at making the micro-CT data exploration of natural history specimens freely available over the internet. The Micro-CT vlab offers to the user virtual image galleries of various taxa which can be displayed and downloaded through a web application. With a few clicks, accurate, detailed and three-dimensional models of species can be studied and virtually dissected without destroying the actual specimen. The data and functions of the Micro-CT vlab can be accessed either on a normal computer or through a dedicated version for mobile devices.

Establishing a process of irradiating small animal brain using a CyberKnife and a microCT scanner

International Nuclear Information System (INIS)

Kim, Haksoo; Welford, Scott; Fabien, Jeffrey; Zheng, Yiran; Yuan, Jake; Brindle, James; Yao, Min; Lo, Simon; Wessels, Barry; Machtay, Mitchell; Sohn, Jason W.; Sloan, Andrew

2014-01-01

Purpose: Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. Methods: These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, with radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system—MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was “printed” using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. Results: For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm). A

Establishing a process of irradiating small animal brain using a CyberKnife and a microCT scanner

Energy Technology Data Exchange (ETDEWEB)

Kim, Haksoo; Welford, Scott [Department of Radiation Oncology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 (United States); Fabien, Jeffrey; Zheng, Yiran; Yuan, Jake; Brindle, James; Yao, Min; Lo, Simon; Wessels, Barry; Machtay, Mitchell; Sohn, Jason W., E-mail: jason.sohn@case.edu [Department of Radiation Oncology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 and University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland, Ohio 44106 (United States); Sloan, Andrew [Department of Neurosurgery, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 (United States)

2014-02-15

Purpose: Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. Methods: These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, with radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system—MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was “printed” using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. Results: For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm

Micro rapid prototyping system for micro components

International Nuclear Information System (INIS)

Li Xiaochun; Choi Hongseok; Yang Yong

2002-01-01

Similarities between silicon-based micro-electro-mechanical systems (MEMS) and Shape Deposition Manufacturing (SDM) processes are obvious: both integrate additive and subtractive processes and use part and sacrificial materials to obtain functional structures. These MEMS techniques are two-dimensional (2-D) processes for a limited number of materials while SDM enables the building of parts that have traditionally been impossible to fabricate because of their complex shapes or of their variety in materials. This work presents initial results on the development of a micro rapid prototyping system that adapts SDM methodology to micro-fabrication. This system is designed to incorporate microdeposition and laser micromachining. In the hope of obtaining a precise microdeposition, an ultrasonic-based micro powder-feeding mechanism was developed in order to form thin patterns of dry powders that can be cladded or sintered onto a substrate by a micro-sized laser beam. Furthermore, experimental results on laser micromachining using a laser beam with a wavelength of 355 nm are also presented. After further improvement, the developed micro manufacturing system could take computer-aided design (CAD) output to reproduce 3-D heterogeneous micro-components from a wide selection of materials

Comparison of micro-computerized tomography and cone-beam computerized tomography in the detection of accessory canals in primary molars

OpenAIRE

Acar, Buket; Kamburo?lu, K?van?; Tatar, ?lkan; Ar?kan, Volkan; ?elik, Hakan Hamdi; Y?ksel, Selcen; ?zen, Tuncer

2015-01-01

Purpose This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Materials and Methods Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this s...

In-line phase contrast micro-CT reconstruction for biomedical specimens.

Science.gov (United States)

Fu, Jian; Tan, Renbo

2014-01-01

X-ray phase contrast micro computed tomography (micro-CT) can non-destructively provide the internal structure information of soft tissues and low atomic number materials. It has become an invaluable analysis tool for biomedical specimens. Here an in-line phase contrast micro-CT reconstruction technique is reported, which consists of a projection extraction method and the conventional filter back-projection (FBP) reconstruction algorithm. The projection extraction is implemented by applying the Fourier transform to the forward projections of in-line phase contrast micro-CT. This work comprises a numerical study of the method and its experimental verification using a biomedical specimen dataset measured at an X-ray tube source micro-CT setup. The numerical and experimental results demonstrate that the presented technique can improve the imaging contrast of biomedical specimens. It will be of interest for a wide range of in-line phase contrast micro-CT applications in medicine and biology.

A LabVIEW Platform for Preclinical Imaging Using Digital Subtraction Angiography and Micro-CT.

Science.gov (United States)

Badea, Cristian T; Hedlund, Laurence W; Johnson, G Allan

2013-01-01

CT and digital subtraction angiography (DSA) are ubiquitous in the clinic. Their preclinical equivalents are valuable imaging methods for studying disease models and treatment. We have developed a dual source/detector X-ray imaging system that we have used for both micro-CT and DSA studies in rodents. The control of such a complex imaging system requires substantial software development for which we use the graphical language LabVIEW (National Instruments, Austin, TX, USA). This paper focuses on a LabVIEW platform that we have developed to enable anatomical and functional imaging with micro-CT and DSA. Our LabVIEW applications integrate and control all the elements of our system including a dual source/detector X-ray system, a mechanical ventilator, a physiological monitor, and a power microinjector for the vascular delivery of X-ray contrast agents. Various applications allow cardiac- and respiratory-gated acquisitions for both DSA and micro-CT studies. Our results illustrate the application of DSA for cardiopulmonary studies and vascular imaging of the liver and coronary arteries. We also show how DSA can be used for functional imaging of the kidney. Finally, the power of 4D micro-CT imaging using both prospective and retrospective gating is shown for cardiac imaging.

Micro-CT and nano-CT analysis of filling quality of three different endodontic sealers.

Science.gov (United States)

Huang, Yan; Celikten, Berkan; de Faria Vasconcelos, Karla; Ferreira Pinheiro Nicolielo, Laura; Lippiatt, Nicholas; Buyuksungur, Arda; Jacobs, Reinhilde; Orhan, Kaan

2017-12-01

To investigate voids in different root canal sealers using micro-CT and nano-CT, and to explore the feasibility of using nano-CT for quantitative analysis of sealer filling quality. 30 extracted mandibular central incisors were randomly assigned into three groups according to the applied root canal sealers (Total BC Sealer, Sure Seal Root, AH Plus) by the single cone technique. Subsequently, micro-CT and nano-CT were performed to analyse the incidence rate of voids, void fraction, void volume and their distribution in each sample. Micro-CT evaluation showed no significant difference among sealers for the incidence rate of voids or void fraction in the whole filling materials (p > 0.05), whereas a significant difference was found between AH Plus and the other two sealers using nano-CT (p nano-CT results displayed higher void volume in AH Plus among all the sealers and regions (p nano-CT analysis, when round root canals were treated by the single cone technique. The disparate results suggest that the higher resolution of nano-CT have a greater ability of distinguishing internal porosity, and therefore suggesting the potential use of nano-CT in quantitative analysis of filling quality of sealers.

Multi-institutional MicroCT image comparison of image-guided small animal irradiators

Science.gov (United States)

Johnstone, Chris D.; Lindsay, Patricia; E Graves, Edward; Wong, Eugene; Perez, Jessica R.; Poirier, Yannick; Ben-Bouchta, Youssef; Kanesalingam, Thilakshan; Chen, Haijian; E Rubinstein, Ashley; Sheng, Ke; Bazalova-Carter, Magdalena

2017-07-01

To recommend imaging protocols and establish tolerance levels for microCT image quality assurance (QA) performed on conformal image-guided small animal irradiators. A fully automated QA software SAPA (small animal phantom analyzer) for image analysis of the commercial Shelley micro-CT MCTP 610 phantom was developed, in which quantitative analyses of CT number linearity, signal-to-noise ratio (SNR), uniformity and noise, geometric accuracy, spatial resolution by means of modulation transfer function (MTF), and CT contrast were performed. Phantom microCT scans from eleven institutions acquired with four image-guided small animal irradiator units (including the commercial PXi X-RAD SmART and Xstrahl SARRP systems) with varying parameters used for routine small animal imaging were analyzed. Multi-institutional data sets were compared using SAPA, based on which tolerance levels for each QA test were established and imaging protocols for QA were recommended. By analyzing microCT data from 11 institutions, we established image QA tolerance levels for all image quality tests. CT number linearity set to R 2  >  0.990 was acceptable in microCT data acquired at all but three institutions. Acceptable SNR  >  36 and noise levels  1.5 lp mm-1 for MTF  =  0.2) was obtained at all but four institutions due to their large image voxel size used (>0.275 mm). Ten of the eleven institutions passed the set QA tolerance for geometric accuracy (2000 HU for 30 mgI ml-1). We recommend performing imaging QA with 70 kVp, 1.5 mA, 120 s imaging time, 0.20 mm voxel size, and a frame rate of 5 fps for the PXi X-RAD SmART. For the Xstrahl SARRP, we recommend using 60 kVp, 1.0 mA, 240 s imaging time, 0.20 mm voxel size, and 6 fps. These imaging protocols should result in high quality images that pass the set tolerance levels on all systems. Average SAPA computation time for complete QA analysis for a 0.20 mm voxel, 400 slice Shelley phantom microCT data set

Coronary artery wall imaging in mice using osmium tetroxide and micro-computed tomography (micro-CT)

International Nuclear Information System (INIS)

Pai, Vinay M.; Kozlowski, Megan; Donahue, Danielle; Miller, Elishiah; Xiao, Xianghui; Chen, Marcus Y.; Yu, Zu-Xi; Connelly, Patricia; Jeffries, Kenneth; Wen, Han

2012-01-01

The high spatial resolution of micro-computed tomography (micro-CT) is ideal for 3D imaging of coronary arteries in intact mouse heart specimens. Previously, micro-CT of mouse heart specimens utilized intravascular contrast agents that hardened within the vessel lumen and allowed a vascular cast to be made. However, for mouse coronary artery disease models, it is highly desirable to image coronary artery walls and highlight plaques. For this purpose, we describe an ex vivo contrast-enhanced micro-CT imaging technique based on tissue staining with osmium tetroxide (OsO 4 ) solution. As a tissue-staining contrast agent, OsO 4 is retained in the vessel wall and surrounding tissue during the fixation process and cleared from the vessel lumens. Its high X-ray attenuation makes the artery wall visible in CT. Additionally, since OsO 4 preferentially binds to lipids, it highlights lipid deposition in the artery wall. We performed micro-CT of heart specimens of 5- to 25-week-old C57BL/6 wild-type mice and 5- to 13-week-old apolipoprotein E knockout (apoE -/- ) mice at 10 μm resolution. The results show that walls of coronary arteries as small as 45 μm in diameter are visible using a table-top micro-CT scanner. Similar image clarity was achieved with 1/2000th the scan time using a synchrotron CT scanner. In 13-week-old apoE mice, lipid-rich plaques are visible in the aorta. Our study shows that the combination of OsO 4 and micro-CT permits the visualization of the coronary artery wall in intact mouse hearts.

Morphology of Major Stone Types, As Shown by Micro Computed Tomography (micro CT)

International Nuclear Information System (INIS)

Jackson, Molly E.; Beuschel, Christian A.; McAteer, James A.; Williams, James C.

2008-01-01

Micro CT offers the possibility of providing a non-destructive method of stone analysis that allows visualization of 100% of the stone's volume. For the present study, micro CT analysis was completed on stones of known composition with isotropic voxel sizes of either 7 or 9.1 μm. Each mineral type was distinctive, either by x-ray attenuation values or by morphology. Minor components, such as the presence of apatite in oxalate stones, were easily seen. The analysis of stones by micro CT opens up the possibility of exploring the stone as an encapsulated history of the patient's disease, showing changes in mineral deposition with time.

A backprojection-filtration algorithm for nonstandard spiral cone-beam CT with an n-PI-window

International Nuclear Information System (INIS)

Yu Hengyong; Ye Yangbo; Zhao Shiying; Wang Ge

2005-01-01

For applications in bolus-chasing computed tomography (CT) angiography and electron-beam micro-CT, the backprojection-filtration (BPF) formula developed by Zou and Pan was recently generalized by Ye et al to reconstruct images from cone-beam data collected along a rather flexible scanning locus, including a nonstandard spiral. A major implication of the generalized BPF formula is that it can be applied for n-PI-window-based reconstruction in the nonstandard spiral scanning case. In this paper, we design an n-PI-window-based BPF algorithm, and report the numerical simulation results with the 3D Shepp-Logan phantom and Defrise disk phantom. The proposed BPF algorithm consists of three steps: cone-beam data differentiation, weighted backprojection and inverse Hilbert filtration. Our simulated results demonstrate the feasibility and merits of the proposed algorithm

Micro computed tomography (CT) scanned anatomical gateway to insect pest bioinformatics

Science.gov (United States)

An international collaboration to establish an interactive Digital Video Library for a Systems Biology Approach to study the Asian citrus Psyllid and psyllid genomics/proteomics interactions is demonstrated. Advances in micro-CT, digital computed tomography (CT) scan uses X-rays to make detailed pic...

Effect of reciprocating systems and working lengths on apical microcrack development: a micro-CT Study

International Nuclear Information System (INIS)

Oliveira, Bruna Paloma de; Câmara, Andréa Cruz; Duarte, Daniel Amancio; Antonino, Antonio Celso Dantas; Aguiar, Carlos Menezes; Heck, Richard John

2017-01-01

The objective of this study was to evaluate the effect of root canal preparation with single-file reciprocating systems at different working lengths on the development of apical microcracks using micro-computed tomographic (micro-CT) imaging. Forty extracted human mandibular incisors were randomly assigned to 4 groups (n=10) according to the systems and working length used to prepare the root canals: Group A - WaveOne Gold at apical foramen (AF), Group B - WaveOne Gold 1 mm short of the AF (AF-1 mm), Group C - Unicone (AF) and Group D - Unicone (AF-1 mm). Micro-CT scanning was performed before and after root canal preparation at an isotropic resolution of 14 μm. Then, three examiners assessed the cross-sectional images generated to detect microcracks in the apical portion of the roots. Apical microcracks were visualized in 3, 1, 1, and 3 specimens in groups A, B, C, and D, respectively. All these microcracks observed after root canal preparation already existed prior to instrumentation, and no new apical microcrack was detected. For all groups, the number of slices presenting microcracks after root canal preparation was the same as before canal preparation. Root canal preparation with WaveOne Gold and Unicone, regardless of the working length, was not associated with apical microcrack formation. (author)

Effect of reciprocating systems and working lengths on apical microcrack development: a micro-CT Study

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Bruna Paloma de; Câmara, Andréa Cruz; Duarte, Daniel Amancio; Antonino, Antonio Celso Dantas; Aguiar, Carlos Menezes, E-mail: bruna_paloma@msn.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Heck, Richard John [Department of Land Resource Science, University of Guelph (Canada)

2017-11-15

The objective of this study was to evaluate the effect of root canal preparation with single-file reciprocating systems at different working lengths on the development of apical microcracks using micro-computed tomographic (micro-CT) imaging. Forty extracted human mandibular incisors were randomly assigned to 4 groups (n=10) according to the systems and working length used to prepare the root canals: Group A - WaveOne Gold at apical foramen (AF), Group B - WaveOne Gold 1 mm short of the AF (AF-1 mm), Group C - Unicone (AF) and Group D - Unicone (AF-1 mm). Micro-CT scanning was performed before and after root canal preparation at an isotropic resolution of 14 μm. Then, three examiners assessed the cross-sectional images generated to detect microcracks in the apical portion of the roots. Apical microcracks were visualized in 3, 1, 1, and 3 specimens in groups A, B, C, and D, respectively. All these microcracks observed after root canal preparation already existed prior to instrumentation, and no new apical microcrack was detected. For all groups, the number of slices presenting microcracks after root canal preparation was the same as before canal preparation. Root canal preparation with WaveOne Gold and Unicone, regardless of the working length, was not associated with apical microcrack formation. (author)

Cone-beam micro-CT system based on LabVIEW software.

Science.gov (United States)

Ionita, Ciprian N; Hoffmann, Keneth R; Bednarek, Daniel R; Chityala, Ravishankar; Rudin, Stephen

2008-09-01

Construction of a cone-beam computed tomography (CBCT) system for laboratory research usually requires integration of different software and hardware components. As a result, building and operating such a complex system require the expertise of researchers with significantly different backgrounds. Additionally, writing flexible code to control the hardware components of a CBCT system combined with designing a friendly graphical user interface (GUI) can be cumbersome and time consuming. An intuitive and flexible program structure, as well as the program GUI for CBCT acquisition, is presented in this note. The program was developed in National Instrument's Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW) graphical language and is designed to control a custom-built CBCT system but has been also used in a standard angiographic suite. The hardware components are commercially available to researchers and are in general provided with software drivers which are LabVIEW compatible. The program structure was designed as a sequential chain. Each step in the chain takes care of one or two hardware commands at a time; the execution of the sequence can be modified according to the CBCT system design. We have scanned and reconstructed over 200 specimens using this interface and present three examples which cover different areas of interest encountered in laboratory research. The resulting 3D data are rendered using a commercial workstation. The program described in this paper is available for use or improvement by other researchers.

The effect of spatial micro-CT image resolution and surface complexity on the morphological 3D analysis of open porous structures

Energy Technology Data Exchange (ETDEWEB)

Pyka, Grzegorz, E-mail: gregory.pyka@mtm.kuleuven.be [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 – PB2450, B-3001 Leuven (Belgium); Kerckhofs, Greet [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 – PB2450, B-3001 Leuven (Belgium); Biomechanics Research Unit, Université de Liege, Chemin des Chevreuils 1 - BAT 52/3, B-4000 Liège (Belgium); Schrooten, Jan; Wevers, Martine [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 – PB2450, B-3001 Leuven (Belgium)

2014-01-15

In material science microfocus X-ray computed tomography (micro-CT) is one of the most popular non-destructive techniques to visualise and quantify the internal structure of materials in 3D. Despite constant system improvements, state-of-the-art micro-CT images can still hold several artefacts typical for X-ray CT imaging that hinder further image-based processing, structural and quantitative analysis. For example spatial resolution is crucial for an appropriate characterisation as the voxel size essentially influences the partial volume effect. However, defining the adequate image resolution is not a trivial aspect and understanding the correlation between scan parameters like voxel size and the structural properties is crucial for comprehensive material characterisation using micro-CT. Therefore, the objective of this study was to evaluate the influence of the spatial image resolution on the micro-CT based morphological analysis of three-dimensional (3D) open porous structures with a high surface complexity. In particular the correlation between the local surface properties and the accuracy of the micro-CT-based macro-morphology of 3D open porous Ti6Al4V structures produced by selective laser melting (SLM) was targeted and revealed for rough surfaces a strong dependence of the resulting structure characteristics on the scan resolution. Reducing the surface complexity by chemical etching decreased the sensitivity of the overall morphological analysis to the spatial image resolution and increased the detection limit. This study showed that scan settings and image processing parameters need to be customized to the material properties, morphological parameters under investigation and the desired final characteristics (in relation to the intended functional use). Customization of the scan resolution can increase the reliability of the micro-CT based analysis and at the same time reduce its operating costs. - Highlights: • We examine influence of the image resolution

Laser beam micro-milling of micro-channels in aerospace alloys

CERN Document Server

Ahmed, Naveed; Al-Ahmari, Abdulrahman

2017-01-01

This volume is greatly helpful to micro-machining and laser engineers as it offers obliging guidelines about the micro-channel fabrications through Nd:YAG laser beam micro-milling. The book also demonstrates how the laser beam micro-milling behaves when operating under wet conditions (under water), and explores what are the pros and cons of this hybrid technique. From the predictive mathematical models, the readers can easily estimate the resulting micro-channel size against the desired laser parametric combinations. The book considers micro-channels in three highly important research materials commonly used in aerospace industry: titanium alloy Ti-6Al-4V, nickel alloy Inconel 718 and aluminum alloy AA 2024. Therefore, the book is highly practicable in the fields of micro-channel heat exchangers, micro-channel aerospace turbine blades, micro-channel heat pipes, micro-coolers and micro-channel pulsating heat plates. These are frequently used in various industries such as aerospace, automotive, biomedical and m...

Three-dimensional evaluation of human jaw bone microarchitecture: correlation between the microarchitectural parameters of cone beam computed tomography and micro-computer tomography.

Science.gov (United States)

Kim, Jo-Eun; Yi, Won-Jin; Heo, Min-Suk; Lee, Sam-Sun; Choi, Soon-Chul; Huh, Kyung-Hoe

2015-12-01

To evaluate the potential feasibility of cone beam computed tomography (CBCT) in the assessment of trabecular bone microarchitecture. Sixty-eight specimens from four pairs of human jaw were scanned using both micro-computed tomography (micro-CT) of 19.37-μm voxel size and CBCT of 100-μm voxel size. The correlation of 3-dimensional parameters between CBCT and micro-CT was evaluated. All parameters, except bone-specific surface and trabecular thickness, showed linear correlations between the 2 imaging modalities (P < .05). Among the parameters, bone volume, percent bone volume, trabecular separation, and degree of anisotropy (DA) of CBCT images showed strong correlations with those of micro-CT images. DA showed the strongest correlation (r = 0.693). Most microarchitectural parameters from CBCT were correlated with those from micro-CT. Some microarchitectural parameters, especially DA, could be used as strong predictors of bone quality in the human jaw. Copyright © 2015 Elsevier Inc. All rights reserved.

Monte Carlo dosimetry of iodine contrast objects in a small animal microCT

Energy Technology Data Exchange (ETDEWEB)

Rodriguez-Villafuerte, M., E-mail: mercedes@fisica.unam.mx [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A.P. 20-364, 01000 Mexico D.F. (Mexico); Martinez-Davalos, A. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A.P. 20-364, 01000 Mexico D.F. (Mexico)

2011-08-21

Small animal microcomputed tomography (microCT) studies with iodine-based contrast media are commonly used in preclinical research. While the use of contrast media improves the quality of the images, it can also result in an increase in the absorbed dose to organs with high concentration of the contrast agent, which might cause radiation damage to the animal. In this work we present the results of a Monte Carlo investigation of a microCT dosimetry study using mouse-sized cylindrical water phantoms with iodine contrast insets for different X-ray spectra (Mo and W targets, 30-80 kVp), iodine concentrations (0, 5, 10 and 15 mg mL{sup -1}) and contrast object sizes (3 and 10 mm diameter). Our results indicate an absorbed dose increase in the contrast-inset regions with respect to the absorbed dose distribution within a reference uniform water phantom. The calculated spatial absorbed dose distributions show large gradients due to beam hardening effects, and large absorbed dose enhancement as the mean energy of the beam and iodine concentration increase. We have found that absorbed doses in iodine contrast objects can increase by a factor of up to 12 for a realistic 80 kVp X-ray spectra and an iodine concentration of 15 mg mL{sup -1}.

Study on broad beam heavy ion CT

International Nuclear Information System (INIS)

Ohno, Yumiko; Kohno, Toshiyuki; Sasaki, Hitomi; Nanbu, S.; Kanai, Tatsuaki

2003-01-01

To achieve the heavy ion radiotherapy more precisely, it is important to know the distribution of the electron density in a human body, which is highly related to the range of charged particles. From a heavy ion CT image, we can directly obtain the 2-D distribution of the electron density in a sample. For this purpose, we have developed a broad beam heavy ion CT system. The electron density was obtained using some kinds of solutions targets. Also the dependence of the spatial resolution on the target size and the kinds of beams was estimated in this work using cylinders targets of 40, 60 and 80 mm in diameter, each of them has a hole of 10 mm in diameter at the center of it. (author)

Study of squeeze film damping in a micro-beam resonator based on micro-polar theory

Directory of Open Access Journals (Sweden)

Mina Ghanbari

Full Text Available In this paper, squeeze film damping in a micro-beam resonator based on micro-polar theory has been investigated. The proposed model for this study consists of a clamped-clamped micro-beam bounded between two fixed layers. The gap between the micro-beam and layers is filled with air. As fluid behaves differently in micro scale than macro, the micro-scale fluid field in the gap has been modeled based on micro-polar theory. Equation of motion governing transverse deflection of the micro- beam based on modified couple stress theory and also non-linear Reynolds equation of the fluid field based on micropolar theory have been non-dimensionalized, linearized and solved simultaneously in order to calculate the quality factor of the resonator. The effect of micropolar parameters of air on the quality factor has been investigated. The quality factor of the of the micro-beam resonator for different values of non-dimensionalized length scale of the beam, squeeze number and also non-dimensionalized pressure has been calculated and compared to the obtained values of quality factor based on classical theory.

A robotic C-arm cone beam CT system for image-guided proton therapy: design and performance.

Science.gov (United States)

Hua, Chiaho; Yao, Weiguang; Kidani, Takao; Tomida, Kazuo; Ozawa, Saori; Nishimura, Takenori; Fujisawa, Tatsuya; Shinagawa, Ryousuke; Merchant, Thomas E

2017-11-01

A ceiling-mounted robotic C-arm cone beam CT (CBCT) system was developed for use with a 190° proton gantry system and a 6-degree-of-freedom robotic patient positioner. We report on the mechanical design, system accuracy, image quality, image guidance accuracy, imaging dose, workflow, safety and collision-avoidance. The robotic CBCT system couples a rotating C-ring to the C-arm concentrically with a kV X-ray tube and a flat-panel imager mounted to the C-ring. CBCT images are acquired with flex correction and maximally 360° rotation for a 53 cm field of view. The system was designed for clinical use with three imaging locations. Anthropomorphic phantoms were imaged to evaluate the image guidance accuracy. The position accuracy and repeatability of the robotic C-arm was high (robotic CBCT system provides high-accuracy volumetric image guidance for proton therapy. Advances in knowledge: Ceiling-mounted robotic CBCT provides a viable option than CT on-rails for partial gantry and fixed-beam proton systems with the added advantage of acquiring images at the treatment isocentre.

Low-dose dual-energy cone-beam CT using a total-variation minimization algorithm

International Nuclear Information System (INIS)

Min, Jong Hwan

2011-02-01

Dual-energy cone-beam CT is an important imaging modality in diagnostic applications, and may also find its use in other application such as therapeutic image guidance. Despite of its clinical values, relatively high radiation dose of dual-energy scan may pose a challenge to its wide use. In this work, we investigated a low-dose, pre-reconstruction type of dual-energy cone-beam CT (CBCT) using a total-variation minimization algorithm for image reconstruction. An empirical dual-energy calibration method was used to prepare material-specific projection data. Raw data at high and low tube voltages are converted into a set of basis functions which can be linearly combined to produce material-specific data using the coefficients obtained through the calibration process. From much fewer views than are conventionally used, material specific images are reconstructed by use of the total-variation minimization algorithm. An experimental study was performed to demonstrate the feasibility of the proposed method using a micro-CT system. We have reconstructed images of the phantoms from only 90 projections acquired at tube voltages of 40 kVp and 90 kVp each. Aluminum-only and acryl-only images were successfully decomposed. We evaluated the quality of the reconstructed images by use of contrast-to-noise ratio and detectability. A low-dose dual-energy CBCT can be realized via the proposed method by greatly reducing the number of projections

Low-dose cardio-respiratory phase-correlated cone-beam micro-CT of small animals.

Science.gov (United States)

Sawall, Stefan; Bergner, Frank; Lapp, Robert; Mronz, Markus; Karolczak, Marek; Hess, Andreas; Kachelriess, Marc

2011-03-01

Micro-CT imaging of animal hearts typically requires a double gating procedure because scans during a breath-hold are not possible due to the long scan times and the high respiratory rates, Simultaneous respiratory and cardiac gating can either be done prospectively or retrospectively. True five-dimensional information can be either retrieved with retrospective gating or with prospective gating if several prospective gates are acquired. In any case, the amount of information available to reconstruct one volume for a given respiratory and cardiac phase is orders of magnitud lower than the total amount of information acquired. For example, the reconstruction of a volume from a 10% wide respiratory and a 20% wide cardiac window uses only 2% of the data acquired. Achieving a similar image quality as a nongated scan would therefore require to increase the amount of data and thereby the dose to the animal by up to a factor of 50. To achieve the goal of low-dose phase-correlated (LDPC) imaging, the authors propose to use a highly efficient combination of slightly modified existing algorithms. In particular, the authors developed a variant of the McKinnon-Bates image reconstruction algorithm and combined it with bilateral filtering in up to five dimensions to significantly reduce image noise without impairing spatial or temporal resolution. The preliminary results indicate that the proposed LDPC reconstruction method typically reduces image noise by a factor of up to 6 (e.g., from 170 to 30 HU), while the dose values lie in a range from 60 to 500 mGy. Compared to other publications that apply 250-1800 mGy for the same task [C. T. Badea et al., "4D micro-CT of the mouse heart," Mol. Imaging 4(2), 110-116 (2005); M. Drangova et al., "Fast retrospectively gated quantitative four-dimensional (4D) cardiac micro computed tomography imaging of free-breathing mice," Invest. Radiol. 42(2), 85-94 (2007); S. H. Bartling et al., "Retrospective motion gating in small animal CT of mice

Optimisation of a propagation-based x-ray phase-contrast micro-CT system

Science.gov (United States)

Nesterets, Yakov I.; Gureyev, Timur E.; Dimmock, Matthew R.

2018-03-01

Micro-CT scanners find applications in many areas ranging from biomedical research to material sciences. In order to provide spatial resolution on a micron scale, these scanners are usually equipped with micro-focus, low-power x-ray sources and hence require long scanning times to produce high resolution 3D images of the object with acceptable contrast-to-noise. Propagation-based phase-contrast tomography (PB-PCT) has the potential to significantly improve the contrast-to-noise ratio (CNR) or, alternatively, reduce the image acquisition time while preserving the CNR and the spatial resolution. We propose a general approach for the optimisation of the PB-PCT imaging system. When applied to an imaging system with fixed parameters of the source and detector this approach requires optimisation of only two independent geometrical parameters of the imaging system, i.e. the source-to-object distance R 1 and geometrical magnification M, in order to produce the best spatial resolution and CNR. If, in addition to R 1 and M, the system parameter space also includes the source size and the anode potential this approach allows one to find a unique configuration of the imaging system that produces the required spatial resolution and the best CNR.

Study of bony trabecular characteristics using bone morphometry and micro-CT

International Nuclear Information System (INIS)

Song, Young Han; Lee, Wan; Lee, Chang Jin; Ji, Jung Hyun; Lee, Byung Do

2007-01-01

The research was done to investigate the effectiveness of 2D bony morphometry and microstructure of micro-computed tomography (micro-CT) on the osteoporotic bony change. We performed the bone morphometric analysis of proximal femur in ovariectomized rabbits with BMD and micro-CT examination. Twenty-one female (Newzeland, about 16 weeks old, 2.9-3.4 kg) rabbits were used. Three rabbits were sacrificed on the day when experiment began (Basline). The remaining 18 rabbits were divided into two groups. One group was ovariectomized bilaterally (OVX) and the other animals were subjected to sham operation (Sham). Bone specimens were obtained from the right and left femur of sacrificed rabbits. At intervals of 1,2,3,5,6 months respectively, BMD tests were performed on the proximal on the proximal femur by using PIXImus 2 (GE Lunar Co. USA), 2-dimensional bone morphometric analysis by custom computer program and 2D / 3D bone structure analysis by micro-CT (Skyscan1072, Antwerpen, Belgium). Statistical analysis was carried out for the correlation between bone morphometry, micro-CT and BMD. BV/TV, Tb.Th, Tb.N of micro-CT parameters showed higher values in sham group than OVX group. N.Nd/Ar.RI, N.NdNd, N.NdTm, N. TmTm, PmB/Ar.RI, 3-D BoxSlope of 2D morphometric parameters showed higher values in Sham group than OVX group. The micro-CT parameters of Tb.Sp. Tb.N were statistically significant correlated with BMD respectively. Several 2D morphometric parameters were statistically significant correlated with BMD respectively. Several parameters of 2D bony morphometry and micro-CT showed effective aspects on the osteoporotic bony change

Automatic calibration method of voxel size for cone-beam 3D-CT scanning system

International Nuclear Information System (INIS)

Yang Min; Wang Xiaolong; Wei Dongbo; Liu Yipeng; Meng Fanyong; Li Xingdong; Liu Wenli

2014-01-01

For a cone-beam three-dimensional computed tomography (3D-CT) scanning system, voxel size is an important indicator to guarantee the accuracy of data analysis and feature measurement based on 3D-CT images. Meanwhile, the voxel size changes with the movement of the rotary stage along X-ray direction. In order to realize the automatic calibration of the voxel size, a new and easily-implemented method is proposed. According to this method, several projections of a spherical phantom are captured at different imaging positions and the corresponding voxel size values are calculated by non-linear least-square fitting. Through these interpolation values, a linear equation is obtained that reflects the relationship between the voxel size and the rotary stage translation distance from its nominal zero position. Finally, the linear equation is imported into the calibration module of the 3D-CT scanning system. When the rotary stage is moving along X-ray direction, the accurate value of the voxel size is dynamically exported. The experimental results prove that this method meets the requirements of the actual CT scanning system, and has virtues of easy implementation and high accuracy. (authors)

Micro-CT assessment of two different endodontic preparation systems

Directory of Open Access Journals (Sweden)

Cacio Moura-Netto

2013-02-01

Full Text Available The aim of this study was to compare two endodontic preparation systems using micro-CT analysis. Twenty-four one-rooted mandibular premolars were selected and randomly assigned to two groups. The samples (n = 12 of Group 1 were prepared using the ProTaper Universal rotary system, while Group 2 (n = 12 was prepared using the EndoEZE AET system complemented by manual apical preparation with K-type hand files up to #30. A 2.5% sodium hypochlorite solution was used in both groups for irrigating. Both groups were scanned by high-resolution microcomputed tomography before and after preparation (SkyScan 1172, SkyScan, Kontich, Belgium. The root canal volume and surface area was measured before and after preparation, and the differences were calculated and analyzed for statistically significant differences using ANOVA complemented by the Tukey test (p < 0.05. The results showed no statistically significant differences between the mean volumes of dentin removal by the two systems. However, the EndoEZE AET system presented a significantly greater mean surface area compared to the ProTaper system (p < 0.05. The EndoEZE AET system enabled preparation of a greater root canal surface area when compared to the ProTaper Universal system. There seemed to be no difference in dentin volume loss between the two systems used.

Effects of data sampling rate on image quality in fan-beam-CT system

International Nuclear Information System (INIS)

Iwata, Akira; Yamagishi, Nobutoshi; Suzumura, Nobuo; Horiba, Isao.

1984-01-01

Investigation was made into the relationship between spatial resolution or artifacts and data sampling rate in order to pursue the causes of the degradation of CT image quality by computer simulation. First the generation of projection data and reconstruction calculating process are described, and then the results are shown about the relation between angular sampling interval and spatical resolution or artifacts, and about the relation between projection data sampling interval and spatial resolution or artifacts. It was clarified that the formulation of the relationship between spatial resolution and data sampling rate performed so far for parallel X-ray beam was able to be applied to fan beam. As a conclusion, when other reconstruction parameters are the same in fan beam CT systems, spatial resolution can be determined by projection data sampling rate rather than angular sampling rate. The mechanism of artifact generation due to the insufficient number of angular samples was made clear. It was also made clear that there was a definite relationship among measuring region, angular sampling rate and projection data sampling rate, and the amount of artifacts depending upon projection data sampling rate was proportional to the amount of spatial frequency components (Aliasing components) of a test object above the Nyquist frequency of projection data. (Wakatsuki, Y.)

Comparison of micro-computerized tomography and cone-beam computerized tomography in the detection of accessory canals in primary molars.

Science.gov (United States)

Acar, Buket; Kamburoğlu, Kıvanç; Tatar, İlkan; Arıkan, Volkan; Çelik, Hakan Hamdi; Yüksel, Selcen; Özen, Tuncer

2015-12-01

This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman's rho correlation coefficient test. The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images. Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth.

Calibration and analysis of a multimodal micro-CT and structured light imaging system for the evaluation of excised breast tissue

Science.gov (United States)

McClatchy, David M., III; Rizzo, Elizabeth J.; Meganck, Jeff; Kempner, Josh; Vicory, Jared; Wells, Wendy A.; Paulsen, Keith D.; Pogue, Brian W.

2017-12-01

A multimodal micro-computed tomography (CT) and multi-spectral structured light imaging (SLI) system is introduced and systematically analyzed to test its feasibility to aid in margin delineation during breast conserving surgery (BCS). Phantom analysis of the micro-CT yielded a signal-to-noise ratio of 34, a contrast of 1.64, and a minimum detectable resolution of 240 μm for a 1.2 min scan. The SLI system, spanning wavelengths 490 nm to 800 nm and spatial frequencies up to 1.37 mm-1 , was evaluated with aqueous tissue simulating phantoms having variations in particle size distribution, scatter density, and blood volume fraction. The reduced scattering coefficient, μs\\prime and phase function parameter, γ, were accurately recovered over all wavelengths independent of blood volume fractions from 0% to 4%, assuming a flat sample geometry perpendicular to the imaging plane. The resolution of the optical system was tested with a step phantom, from which the modulation transfer function was calculated yielding a maximum resolution of 3.78 cycles per mm. The three dimensional spatial co-registration between the CT and optical imaging space was tested and shown to be accurate within 0.7 mm. A freshly resected breast specimen, with lobular carcinoma, fibrocystic disease, and adipose, was imaged with the system. The micro-CT provided visualization of the tumor mass and its spiculations, and SLI yielded superficial quantification of light scattering parameters for the malignant and benign tissue types. These results appear to be the first demonstration of SLI combined with standard medical tomography for imaging excised tumor specimens. While further investigations are needed to determine and test the spectral, spatial, and CT features required to classify tissue, this study demonstrates the ability of multimodal CT/SLI to quantify, visualize, and spatially navigate breast tumor specimens, which could potentially aid in the assessment of tumor margin status during

Development of high-resolution x-ray CT system using parallel beam geometry

Energy Technology Data Exchange (ETDEWEB)

Yoneyama, Akio, E-mail: akio.yoneyama.bu@hitachi.com; Baba, Rika [Central Research Laboratory, Hitachi Ltd., Hatoyama, Saitama (Japan); Hyodo, Kazuyuki [Institute of Materials Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan); Takeda, Tohoru [School of Allied Health Sciences, Kitasato University, Sagamihara, Kanagawa (Japan); Nakano, Haruhisa; Maki, Koutaro [Department of Orthodontics, School of Dentistry Showa University, Ota-ku, Tokyo (Japan); Sumitani, Kazushi; Hirai, Yasuharu [Kyushu Synchrotron Light Research Center, Tosu, Saga (Japan)

2016-01-28

For fine three-dimensional observations of large biomedical and organic material samples, we developed a high-resolution X-ray CT system. The system consists of a sample positioner, a 5-μm scintillator, microscopy lenses, and a water-cooled sCMOS detector. Parallel beam geometry was adopted to attain a field of view of a few mm square. A fine three-dimensional image of birch branch was obtained using a 9-keV X-ray at BL16XU of SPring-8 in Japan. The spatial resolution estimated from the line profile of a sectional image was about 3 μm.

Demonstration of electronic pattern switching and 10x pattern demagnification in a maskless micro-ion beam reduction lithography system

International Nuclear Information System (INIS)

Ngo, V.V.; Akker, B.; Leung, K.N.; Noh, I.; Scott, K.L.; Wilde, S.

2002-01-01

A proof-of-principle ion projection lithography (IPL) system called Maskless Micro-ion beam Reduction Lithography (MMRL) has been developed and tested at the Lawrence Berkeley National Laboratory (LBNL) for future integrated circuits (ICs) manufacturing and thin film media patterning [1]. This MMRL system is aimed at completely eliminating the first stage of the conventional IPL system [2] that contains the complicated beam optics design in front of the stencil mask and the mask itself. It consists of a multicusp RF plasma generator, a multi-beamlet pattern generator, and an all-electrostatic ion optical column. Results from ion beam exposures on PMMA and Shipley UVII-HS resists using 75 keV H+ are presented in this paper. Proof-of-principle electronic pattern switching together with 10x reduction ion optics (using a pattern generator made of nine 50-(micro)m switchable apertures) has been performed and is reported in this paper. In addition, the fabrication of a micro-fabricated pattern generator [3] on an SOI membrane is also presented

Micro-CT in situ study of carbonate rock microstructural evolution for geologic CO2 storage

DEFF Research Database (Denmark)

Zheng, Yi; Yang, Yan; Rogowska, M.

2017-01-01

to achieve this is to find a suitable condition to create a stable 3D space in carbonate rock by injecting liquid to prepare space for the later CO2 injection. Micro-CT imaging is a non-destructive 3D method that can be used to study the property changes of carbonate rocks during and after CO2 injection....... The advance in lab source based micro-CT has made it capable of in situ experiments. We used a commercial bench top micro-CT (Zeiss Versa XRM410) to study the microstructure changes of chalk during liquid injection. Flexible temporal CT resolution is essential in this study because that the time scales...... of coupled physical and chemical processes can be very different. The results validated the feasibility of using a bench top CT system with a pressure cell to monitor the mesoscale multiphase interactions in chalk....

The dynamic micro computed tomography at SSRF

Science.gov (United States)

Chen, R.; Xu, L.; Du, G.; Deng, B.; Xie, H.; Xiao, T.

2018-05-01

Synchrotron radiation micro-computed tomography (SR-μCT) is a critical technique for quantitative characterizing the 3D internal structure of samples, recently the dynamic SR-μCT has been attracting vast attention since it can evaluate the three-dimensional structure evolution of a sample. A dynamic μCT method, which is based on monochromatic beam, was developed at the X-ray Imaging and Biomedical Application Beamline at Shanghai Synchrotron Radiation Facility, by combining the compressed sensing based CT reconstruction algorithm and hardware upgrade. The monochromatic beam based method can achieve quantitative information, and lower dose than the white beam base method in which the lower energy beam is absorbed by the sample rather than contribute to the final imaging signal. The developed method is successfully used to investigate the compression of the air sac during respiration in a bell cricket, providing new knowledge for further research on the insect respiratory system.

Segmentation-free empirical beam hardening correction for CT

Energy Technology Data Exchange (ETDEWEB)

Schüller, Sören; Sawall, Stefan [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120 (Germany); Stannigel, Kai; Hülsbusch, Markus; Ulrici, Johannes; Hell, Erich [Sirona Dental Systems GmbH, Fabrikstraße 31, 64625 Bensheim (Germany); Kachelrieß, Marc, E-mail: marc.kachelriess@dkfz.de [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)

2015-02-15

proposed algorithm to be segmentation-free (sf). This deformation leads to a nonlinear accentuation of higher CT-values. The original volume and the gray value deformed volume are monochromatically forward projected. The two projection sets are then monomially combined and reconstructed to generate sets of basis volumes which are used for correction. This is done by maximization of the image flatness due to adding additionally a weighted sum of these basis images. sfEBHC is evaluated on polychromatic simulations, phantom measurements, and patient data. The raw data sets were acquired by a dual source spiral CT scanner, a digital volume tomograph, and a dual source micro CT. Different phantom and patient data were used to illustrate the performance and wide range of usability of sfEBHC across different scanning scenarios. The artifact correction capabilities are compared to EBHC. Results: All investigated cases show equal or improved image quality compared to the standard EBHC approach. The artifact correction is capable of correcting beam hardening artifacts for different scan parameters and scan scenarios. Conclusions: sfEBHC generates beam hardening-reduced images and is furthermore capable of dealing with images which are affected by high noise and strong artifacts. The algorithm can be used to recover structures which are hardly visible inside the beam hardening-affected regions.

Segmentation-free empirical beam hardening correction for CT.

Science.gov (United States)

Schüller, Sören; Sawall, Stefan; Stannigel, Kai; Hülsbusch, Markus; Ulrici, Johannes; Hell, Erich; Kachelrieß, Marc

2015-02-01

algorithm to be segmentation-free (sf). This deformation leads to a nonlinear accentuation of higher CT-values. The original volume and the gray value deformed volume are monochromatically forward projected. The two projection sets are then monomially combined and reconstructed to generate sets of basis volumes which are used for correction. This is done by maximization of the image flatness due to adding additionally a weighted sum of these basis images. sfEBHC is evaluated on polychromatic simulations, phantom measurements, and patient data. The raw data sets were acquired by a dual source spiral CT scanner, a digital volume tomograph, and a dual source micro CT. Different phantom and patient data were used to illustrate the performance and wide range of usability of sfEBHC across different scanning scenarios. The artifact correction capabilities are compared to EBHC. All investigated cases show equal or improved image quality compared to the standard EBHC approach. The artifact correction is capable of correcting beam hardening artifacts for different scan parameters and scan scenarios. sfEBHC generates beam hardening-reduced images and is furthermore capable of dealing with images which are affected by high noise and strong artifacts. The algorithm can be used to recover structures which are hardly visible inside the beam hardening-affected regions.

SU-F-J-211: Scatter Correction for Clinical Cone-Beam CT System Using An Optimized Stationary Beam Blocker with a Single Scan

International Nuclear Information System (INIS)

Liang, X; Zhang, Z; Xie, Y; Gong, S; Niu, T; Zhou, Q

2016-01-01

Purpose: X-ray scatter photons result in significant image quality degradation of cone-beam CT (CBCT). Measurement based algorithms using beam blocker directly acquire the scatter samples and achieve significant improvement on the quality of CBCT image. Within existing algorithms, single-scan and stationary beam blocker proposed previously is promising due to its simplicity and practicability. Although demonstrated effectively on tabletop system, the blocker fails to estimate the scatter distribution on clinical CBCT system mainly due to the gantry wobble. In addition, the uniform distributed blocker strips in our previous design results in primary data loss in the CBCT system and leads to the image artifacts due to data insufficiency. Methods: We investigate the motion behavior of the beam blocker in each projection and design an optimized non-uniform blocker strip distribution which accounts for the data insufficiency issue. An accurate scatter estimation is then achieved from the wobble modeling. Blocker wobble curve is estimated using threshold-based segmentation algorithms in each projection. In the blocker design optimization, the quality of final image is quantified using the number of the primary data loss voxels and the mesh adaptive direct search algorithm is applied to minimize the objective function. Scatter-corrected CT images are obtained using the optimized blocker. Results: The proposed method is evaluated using Catphan@504 phantom and a head patient. On the Catphan©504, our approach reduces the average CT number error from 115 Hounsfield unit (HU) to 11 HU in the selected regions of interest, and improves the image contrast by a factor of 1.45 in the high-contrast regions. On the head patient, the CT number error is reduced from 97 HU to 6 HU in the soft tissue region and image spatial non-uniformity is decreased from 27% to 5% after correction. Conclusion: The proposed optimized blocker design is practical and attractive for CBCT guided radiation

SU-F-J-211: Scatter Correction for Clinical Cone-Beam CT System Using An Optimized Stationary Beam Blocker with a Single Scan

Energy Technology Data Exchange (ETDEWEB)

Liang, X; Zhang, Z; Xie, Y [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, GuangDong (China); Gong, S; Niu, T [Department of Radiation Oncology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang (China); Institute of Translational Medicine, Zhejiang University, Hangzhou, Zhejiang (China); Zhou, Q [Department of Radiation Oncology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang (China)

2016-06-15

Purpose: X-ray scatter photons result in significant image quality degradation of cone-beam CT (CBCT). Measurement based algorithms using beam blocker directly acquire the scatter samples and achieve significant improvement on the quality of CBCT image. Within existing algorithms, single-scan and stationary beam blocker proposed previously is promising due to its simplicity and practicability. Although demonstrated effectively on tabletop system, the blocker fails to estimate the scatter distribution on clinical CBCT system mainly due to the gantry wobble. In addition, the uniform distributed blocker strips in our previous design results in primary data loss in the CBCT system and leads to the image artifacts due to data insufficiency. Methods: We investigate the motion behavior of the beam blocker in each projection and design an optimized non-uniform blocker strip distribution which accounts for the data insufficiency issue. An accurate scatter estimation is then achieved from the wobble modeling. Blocker wobble curve is estimated using threshold-based segmentation algorithms in each projection. In the blocker design optimization, the quality of final image is quantified using the number of the primary data loss voxels and the mesh adaptive direct search algorithm is applied to minimize the objective function. Scatter-corrected CT images are obtained using the optimized blocker. Results: The proposed method is evaluated using Catphan@504 phantom and a head patient. On the Catphan©504, our approach reduces the average CT number error from 115 Hounsfield unit (HU) to 11 HU in the selected regions of interest, and improves the image contrast by a factor of 1.45 in the high-contrast regions. On the head patient, the CT number error is reduced from 97 HU to 6 HU in the soft tissue region and image spatial non-uniformity is decreased from 27% to 5% after correction. Conclusion: The proposed optimized blocker design is practical and attractive for CBCT guided radiation

Computerized methodology for micro-CT and histological data inflation using an IVUS based translation map.

Science.gov (United States)

Athanasiou, Lambros S; Rigas, George A; Sakellarios, Antonis I; Exarchos, Themis P; Siogkas, Panagiotis K; Naka, Katerina K; Panetta, Daniele; Pelosi, Gualtiero; Vozzi, Federico; Michalis, Lampros K; Parodi, Oberdan; Fotiadis, Dimitrios I

2015-10-01

A framework for the inflation of micro-CT and histology data using intravascular ultrasound (IVUS) images, is presented. The proposed methodology consists of three steps. In the first step the micro-CT/histological images are manually co-registered with IVUS by experts using fiducial points as landmarks. In the second step the lumen of both the micro-CT/histological images and IVUS images are automatically segmented. Finally, in the third step the micro-CT/histological images are inflated by applying a transformation method on each image. The transformation method is based on the IVUS and micro-CT/histological contour difference. In order to validate the proposed image inflation methodology, plaque areas in the inflated micro-CT and histological images are compared with the ones in the IVUS images. The proposed methodology for inflating micro-CT/histological images increases the sensitivity of plaque area matching between the inflated and the IVUS images (7% and 22% in histological and micro-CT images, respectively). Copyright © 2015 Elsevier Ltd. All rights reserved.

Accuracy of cancellous bone volume fraction measured by micro-CT scanning

DEFF Research Database (Denmark)

Ding, Ming; Odgaard, A; Hvid, I

1999-01-01

Volume fraction, the single most important parameter in describing trabecular microstructure, can easily be calculated from three-dimensional reconstructions of micro-CT images. This study sought to quantify the accuracy of this measurement. One hundred and sixty human cancellous bone specimens...... which covered a large range of volume fraction (9.8-39.8%) were produced. The specimens were micro-CT scanned, and the volume fraction based on Archimedes' principle was determined as a reference. After scanning, all micro-CT data were segmented using individual thresholds determined by the scanner...

GPU-Based 3D Cone-Beam CT Image Reconstruction for Large Data Volume

Directory of Open Access Journals (Sweden)

Xing Zhao

2009-01-01

Full Text Available Currently, 3D cone-beam CT image reconstruction speed is still a severe limitation for clinical application. The computational power of modern graphics processing units (GPUs has been harnessed to provide impressive acceleration of 3D volume image reconstruction. For extra large data volume exceeding the physical graphic memory of GPU, a straightforward compromise is to divide data volume into blocks. Different from the conventional Octree partition method, a new partition scheme is proposed in this paper. This method divides both projection data and reconstructed image volume into subsets according to geometric symmetries in circular cone-beam projection layout, and a fast reconstruction for large data volume can be implemented by packing the subsets of projection data into the RGBA channels of GPU, performing the reconstruction chunk by chunk and combining the individual results in the end. The method is evaluated by reconstructing 3D images from computer-simulation data and real micro-CT data. Our results indicate that the GPU implementation can maintain original precision and speed up the reconstruction process by 110–120 times for circular cone-beam scan, as compared to traditional CPU implementation.

Efficient digitalization method for dental restorations using micro-CT data.

Science.gov (United States)

Kim, Changhwan; Baek, Seung Hoon; Lee, Taewon; Go, Jonggun; Kim, Sun Young; Cho, Seungryong

2017-03-15

The objective of this study was to demonstrate the feasibility of using micro-CT scan of dental impressions for fabricating dental restorations and to compare the dimensional accuracy of dental models generated from various methods. The key idea of the proposed protocol is that dental impression of patients can be accurately digitized by micro-CT scan and that one can make digital cast model from micro-CT data directly. As air regions of the micro-CT scan data of dental impression are equivalent to the real teeth and surrounding structures, one can segment the air regions and fabricate digital cast model in the STL format out of them. The proposed method was validated by a phantom study using a typodont with prepared teeth. Actual measurement and deviation map analysis were performed after acquiring digital cast models for each restoration methods. Comparisons of the milled restorations were also performed by placing them on the prepared teeth of typodont. The results demonstrated that an efficient fabrication of precise dental restoration is achievable by use of the proposed method.

Efficient digitalization method for dental restorations using micro-CT data

Science.gov (United States)

Kim, Changhwan; Baek, Seung Hoon; Lee, Taewon; Go, Jonggun; Kim, Sun Young; Cho, Seungryong

2017-03-01

The objective of this study was to demonstrate the feasibility of using micro-CT scan of dental impressions for fabricating dental restorations and to compare the dimensional accuracy of dental models generated from various methods. The key idea of the proposed protocol is that dental impression of patients can be accurately digitized by micro-CT scan and that one can make digital cast model from micro-CT data directly. As air regions of the micro-CT scan data of dental impression are equivalent to the real teeth and surrounding structures, one can segment the air regions and fabricate digital cast model in the STL format out of them. The proposed method was validated by a phantom study using a typodont with prepared teeth. Actual measurement and deviation map analysis were performed after acquiring digital cast models for each restoration methods. Comparisons of the milled restorations were also performed by placing them on the prepared teeth of typodont. The results demonstrated that an efficient fabrication of precise dental restoration is achievable by use of the proposed method.

Comparison of micro-computerized tomography and cone-beam computerized tomography in the detection of accessory canals in primary molars

Energy Technology Data Exchange (ETDEWEB)

Acar, Buket; Kamburoglu, Kivanc [Dept. of Dentomaxillofacial Radiology, Faculty of Dentistry, Ankara University, Ankara (Turkmenistan); Tatar, Ilkan [Dept. of Anatomy, Faculty of Medicine, Hacettepe University, Ankara (Turkmenistan); Arikan, Volkan [Dept. of Anatomy, Faculty of Medicine, Hacettepe University, Ankara (Turkmenistan); Celik, Hakan Hamid [Dept. of Pediatric Dentistry, Faculty of Dentistry, Kirikkale Unversity, Ankara (Turkmenistan); Yuksel, Selcen [Dept. of Biostatistics, Faculty of Medicine, Yildirim Beyazit University, Ankara (Turkmenistan); Ozen, Tuncer [Dept. of Dentomaxillofacial Radiology, Gulhane Military Hospital, Dental Clinics, Ankara (Turkmenistan)

2015-12-15

This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman's rho correlation coefficient test. The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images.Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth.

Comparison of micro-computerized tomography and cone-beam computerized tomography in the detection of accessory canals in primary molars

International Nuclear Information System (INIS)

Acar, Buket; Kamburoglu, Kivanc; Tatar, Ilkan; Arikan, Volkan; Celik, Hakan Hamid; Yuksel, Selcen; Ozen, Tuncer

2015-01-01

This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman's rho correlation coefficient test. The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images.Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth

Micro-pleural Metastasis Without Effusion: CT and US Findings

International Nuclear Information System (INIS)

Na, Hyoung Il; Yoo, Seung Min; Kim, Yang Soo; Lee, Hwa Yeon; Song, In Sup; Shim, Hyung Jin; Kwak, Byung Kook; Shin, Jong Wook

2004-01-01

Pleural metastasis from malignancy is commonly combined with effusion. We report the ultrasonographic and CT findings in a rare case of micro-pleural metastasis without effusion. A 34-year-old male patient with lung cancer underwent video-assisted thoracoscopic surgery (VATS), prior to open thoracotomy. VATS revealed multiple metastatic micronodules on the pleura, which were overlooked on the preoperative CT scan. The HRCT images and chest ultrasonograms showed clear evidence of pleural micro-nodules

Micro-pleural Metastasis Without Effusion: CT and US Findings

Energy Technology Data Exchange (ETDEWEB)

Na, Hyoung Il; Yoo, Seung Min; Kim, Yang Soo; Lee, Hwa Yeon; Song, In Sup; Shim, Hyung Jin; Kwak, Byung Kook; Shin, Jong Wook [Chung-Ang University College of Medicine, Seoul (Korea, Republic of)

2004-09-15

Pleural metastasis from malignancy is commonly combined with effusion. We report the ultrasonographic and CT findings in a rare case of micro-pleural metastasis without effusion. A 34-year-old male patient with lung cancer underwent video-assisted thoracoscopic surgery (VATS), prior to open thoracotomy. VATS revealed multiple metastatic micronodules on the pleura, which were overlooked on the preoperative CT scan. The HRCT images and chest ultrasonograms showed clear evidence of pleural micro-nodules

MicroCT Scan in paleobiology: application to the study of dental tissues

Energy Technology Data Exchange (ETDEWEB)

Rossi, M.; Casali, F. E-mail: casali@bo.infn.it; Romani, D.; Bondioli, L.; Macchiarelli, R.; Rook, L

2004-01-01

State of the art in paleoanthropological and paleoprimatological research foresees the use of advanced non-destructive investigative approaches. Microcomputed tomography (microCT) is a fundamental tool, since it offers the opportunity to get high quality morphological information with high spatial resolution. We carried out the set-up of an experimental microCT system able to examine paleobiological samples. The equipment can operate on small objects (size up to 3 cm) with a nominal spatial resolution of 30 {mu}m, allowing their 3D volume reconstruction and morphometric analysis. This approach represents a forefront technique in paleobiological studies, successfully employed only in a limited number of advanced research centers. A specific program of microCT analysis has been planned on a sample of human and non-human fossil primate dentitions, in order to assess the specific nature of a number of tooth lesions (e.g. caries versus abrasion). This currently in progress experimental activity represents the first step for the set-up of a research center specifically devoted to the realization of advanced studies in the field of archaeo-paleobiology.

Fast parallel diffractive multi-beam femtosecond laser surface micro-structuring

Energy Technology Data Exchange (ETDEWEB)

Zheng Kuang, E-mail: z.kuang@liv.ac.uk [Laser Group, Department of Engineering, University of Liverpool, Brodie Building, Liverpool L69 3GQ (United Kingdom); Dun Liu; Perrie, Walter; Edwardson, Stuart; Sharp, Martin; Fearon, Eamonn; Dearden, Geoff; Watkins, Ken [Laser Group, Department of Engineering, University of Liverpool, Brodie Building, Liverpool L69 3GQ (United Kingdom)

2009-04-15

Fast parallel femtosecond laser surface micro-structuring is demonstrated using a spatial light modulator (SLM). The Gratings and Lenses algorithm, which is simple and computationally fast, is used to calculate computer generated holograms (CGHs) producing diffractive multiple beams for the parallel processing. The results show that the finite laser bandwidth can significantly alter the intensity distribution of diffracted beams at higher angles resulting in elongated hole shapes. In addition, by synchronisation of applied CGHs and the scanning system, true 3D micro-structures are created on Ti6Al4V.

Characterization of CT beams using Compton spectrometry; Caracterização de feixes de TC utilizando Espectrometria Compton

Energy Technology Data Exchange (ETDEWEB)

Terini, Ricardo A.; Nerssissian, Denise Y.; Campelo, Maria Carolina S.; Yoshimura, Elisabeth M., E-mail: rterini@if.usp.br [Universidade de São Paulo (LDRFM/USP), SP (Brazil). Lab. de Dosimetria das Radiações e Física Médica

2017-07-01

Obtaining the energy spectra of computed tomography (CT) X-ray beams is essential, helping to obtain parameters that characterize beam quality and equipment performance. However, CT photon fluxes are too high to have the spectra measured directly with common photon counting detectors. In this work, a Compton spectrometer was designed, with Al-Pb-Al collimators and shields, as well as a cadmium telluride (CdTe) detector to get the spectrum of CT beams, from the measurement of the spectrum of a beam scattered at 90 deg by a polymethyl-methacrylate (PMMA) rod. A MatLab® computer code was developed, using the Waller-Hartree formalism, to reconstruct the spectrum of the incident beam, from the measured scattered beam spectrum. Tests at IF-USP Laboratory of Radiation Dosimetry and Medical Physics with standard CT beams showed that the reconstructed spectrum is alike the directly measured beam. Shielding influence and scatterer thickness were investigated. The system was tested in measurements on a GE 690 CT scanner, showing practical positioning on the exam table, and alignment with CT lasers refined by scan projection radiography. Spectra obtained with the properly shielded system presented values of half-value layer (HVL) compatible with those measured in QC tests and kVp values with accuracy to evaluate the scanner voltage calibration. (author)

Quantification of in-stent restenosis parameters in rabbits by micro-CT

International Nuclear Information System (INIS)

Langheinrich, A.C.; Zoerb, C.; Jajima, J.; Lommel, D.; Rau, W.S.; Walker, G.; Mueller, K.M.; Bohle, R.M.

2005-01-01

Purpose: The well-defined model of angioplasty and stent implantation in the rabbit aorta is useful in experimental studies of restenosis. This study was performed to evaluate the feasibility of Micro-CT for quantification of in-stent restenosis in a rabbit aortic in-stent restenosis model. Material and Methods: To induce in-stent restenosis seven female New Zealand rabbits underwent balloon dilation and denudation prior to stenting the abdominal aorta. After six weeks on atherogenic diet, animals were killed and the aorta was perfused with contrast agent. Micro-CT morphometric analysis of balloon and stent injured arteries obtained by 700 transverse sections (voxel size 10 μm) was compared to conventional histological analysis. Results: Intimal hyperplasia was present in stented and balloon injured arteries with a moderate intimal area assessed by Micro-CT and conventional histology (3.91±0.5 mm 2 vs. 4.18±0.42; r=0.9). High significant correlations between Micro-CT image analysis and conventional histomorphometry were obtained for lesion size, size of media, size of lumen and stent area (r=0.84 to 0.96). Conclusion: Micro-CT is feasible for quantitative information about restenosis following balloon angioplasty and stent implantation and has the potential to become a standard technique in many laboratories which will augment serial histology as the reference method for ex-vivo studies of restenosis. (orig.)

In Vivo Respiratory-Gated Micro-CT Imaging in Small-Animal Oncology Models

Directory of Open Access Journals (Sweden)

Dawn Cavanaugh

2004-01-01

Full Text Available Micro-computed tomography (micro-CT is becoming an accepted research tool for the noninvasive examination of laboratory animals such as mice and rats, but to date, in vivo scanning has largely been limited to the evaluation of skeletal tissues. We use a commercially available micro-CT device to perform respiratory gated in vivo acquisitions suitable for thoracic imaging. The instrument is described, along with the scan protocol and animal preparation techniques. Preliminary results confirm that lung tumors as small as 1 mm in diameter are visible in vivo with these methods. Radiation dose was evaluated using several approaches, and was found to be approximately 0.15 Gy for this respiratory-gated micro-CT imaging protocol. The combination of high-resolution CT imaging and respiratory-gated acquisitions appears well-suited to serial in vivo scanning.

Spectral optimization for micro-CT

International Nuclear Information System (INIS)

Hupfer, Martin; Nowak, Tristan; Brauweiler, Robert; Eisa, Fabian; Kalender, Willi A.

2012-01-01

Purpose: To optimize micro-CT protocols with respect to x-ray spectra and thereby reduce radiation dose at unimpaired image quality. Methods: Simulations were performed to assess image contrast, noise, and radiation dose for different imaging tasks. The figure of merit used to determine the optimal spectrum was the dose-weighted contrast-to-noise ratio (CNRD). Both optimal photon energy and tube voltage were considered. Three different types of filtration were investigated for polychromatic x-ray spectra: 0.5 mm Al, 3.0 mm Al, and 0.2 mm Cu. Phantoms consisted of water cylinders of 20, 32, and 50 mm in diameter with a central insert of 9 mm which was filled with different contrast materials: an iodine-based contrast medium (CM) to mimic contrast-enhanced (CE) imaging, hydroxyapatite to mimic bone structures, and water with reduced density to mimic soft tissue contrast. Validation measurements were conducted on a commercially available micro-CT scanner using phantoms consisting of water-equivalent plastics. Measurements on a mouse cadaver were performed to assess potential artifacts like beam hardening and to further validate simulation results. Results: The optimal photon energy for CE imaging was found at 34 keV. For bone imaging, optimal energies were 17, 20, and 23 keV for the 20, 32, and 50 mm phantom, respectively. For density differences, optimal energies varied between 18 and 50 keV for the 20 and 50 mm phantom, respectively. For the 32 mm phantom and density differences, CNRD was found to be constant within 2.5% for the energy range of 21–60 keV. For polychromatic spectra and CMs, optimal settings were 50 kV with 0.2 mm Cu filtration, allowing for a dose reduction of 58% compared to the optimal setting for 0.5 mm Al filtration. For bone imaging, optimal tube voltages were below 35 kV. For soft tissue imaging, optimal tube settings strongly depended on phantom size. For 20 mm, low voltages were preferred. For 32 mm, CNRD was found to be almost independent

Spectral optimization for micro-CT.

Science.gov (United States)

Hupfer, Martin; Nowak, Tristan; Brauweiler, Robert; Eisa, Fabian; Kalender, Willi A

2012-06-01

To optimize micro-CT protocols with respect to x-ray spectra and thereby reduce radiation dose at unimpaired image quality. Simulations were performed to assess image contrast, noise, and radiation dose for different imaging tasks. The figure of merit used to determine the optimal spectrum was the dose-weighted contrast-to-noise ratio (CNRD). Both optimal photon energy and tube voltage were considered. Three different types of filtration were investigated for polychromatic x-ray spectra: 0.5 mm Al, 3.0 mm Al, and 0.2 mm Cu. Phantoms consisted of water cylinders of 20, 32, and 50 mm in diameter with a central insert of 9 mm which was filled with different contrast materials: an iodine-based contrast medium (CM) to mimic contrast-enhanced (CE) imaging, hydroxyapatite to mimic bone structures, and water with reduced density to mimic soft tissue contrast. Validation measurements were conducted on a commercially available micro-CT scanner using phantoms consisting of water-equivalent plastics. Measurements on a mouse cadaver were performed to assess potential artifacts like beam hardening and to further validate simulation results. The optimal photon energy for CE imaging was found at 34 keV. For bone imaging, optimal energies were 17, 20, and 23 keV for the 20, 32, and 50 mm phantom, respectively. For density differences, optimal energies varied between 18 and 50 keV for the 20 and 50 mm phantom, respectively. For the 32 mm phantom and density differences, CNRD was found to be constant within 2.5% for the energy range of 21-60 keV. For polychromatic spectra and CMs, optimal settings were 50 kV with 0.2 mm Cu filtration, allowing for a dose reduction of 58% compared to the optimal setting for 0.5 mm Al filtration. For bone imaging, optimal tube voltages were below 35 kV. For soft tissue imaging, optimal tube settings strongly depended on phantom size. For 20 mm, low voltages were preferred. For 32 mm, CNRD was found to be almost independent of tube voltage. For 50 mm

Prospective respiratory-gated micro-CT of free breathing rodents

International Nuclear Information System (INIS)

Ford, Nancy L.; Nikolov, Hristo N.; Norley, Chris J.D.; Thornton, Michael M.; Foster, Paula J.; Drangova, Maria; Holdsworth, David W.

2005-01-01

Microcomputed tomography (Micro-CT) has the potential to noninvasively image the structure of organs in rodent models with high spatial resolution and relatively short image acquisition times. However, motion artifacts associated with the normal respiratory motion of the animal may arise when imaging the abdomen or thorax. To reduce these artifacts and the accompanying loss of spatial resolution, we propose a prospective respiratory gating technique for use with anaesthetized, free-breathing rodents. A custom-made bed with an embedded pressure chamber was connected to a pressure transducer. Anaesthetized animals were placed in the prone position on the bed with their abdomens located over the chamber. During inspiration, the motion of the diaphragm caused an increase in the chamber pressure, which was converted into a voltage signal by the transducer. An output voltage was used to trigger image acquisition at any desired time point in the respiratory cycle. Digital radiographic images were acquired of anaesthetized, free-breathing rats with a digital radiographic system to correlate the respiratory wave form with respiration-induced organ motion. The respiratory wave form was monitored and recorded simultaneously with the x-ray radiation pulses, and an imaging window was defined, beginning at end expiration. Phantom experiments were performed to verify that the respiratory gating apparatus was triggering the micro-CT system. Attached to the distensible phantom were 100 μm diameter copper wires and the measured full width at half maximum was used to assess differences in image quality between respiratory-gated and ungated imaging protocols. This experiment allowed us to quantify the improvement in the spatial resolution, and the reduction of motion artifacts caused by moving structures, in the images resulting from respiratory-gated image acquisitions. The measured wire diameters were 0.135 mm for the stationary phantom image, 0.137 mm for the image gated at end

Estimation of effective dose from limited cone beam X-ray CT examination

Energy Technology Data Exchange (ETDEWEB)

Iwai, Kazuo; Arai, Yoshinori; Hashimoto, Koji [Nihon Univ., Tokyo (Japan). School of Dentistry; Nishizawa, Kanae

2000-12-01

The limited cone beam X-ray CT (Ortho-CT) was developed on the basis of multi-functional panoramic apparatus, SCANORA (Soredex Co. Helsinki Finland). The imaging intensifier (I.I.) was built in this apparatus as a X-ray detection device instead of X-ray film. The signal provided from I.I. was converted from analog into digital by an analog-digital converter and image reconstitution was done as a three-directional image of the dimensions 3.8 cm of width, 3.0 cm height and 3.8 cm depth with the personal computer. The 3DX Multi image micro CT'' (3DX) was developed along similar lines by MORITA Co., Ltd. (Kyoto, JAPAN). In this study, the stochastic effect on organ and tissue caused by examinations using Ortho-CT and 3DX was measured. The effective dose was estimated according to the recommendation of ICRP60 and was compared with those of panoramic radiography and computed tomography. The irradiation conditions were as follows: 85 kV, 10 mA with the filtration of 3 mmAl and added 1 mmCu for Ortho-CT, and 80 kV, 2 mA and the filtration of 3.1 mmAL for 3DX. The measurement of organ and tissue dose was performed using an anthropomorphic Rando woman phantom (Alderson Research Laboratories Co., Stanfora, CN), as well as by using two different type of thermoluminescent dosimeter (TLD); Panasonic UD-170A (BeO) and UD-110S (CaSO{sub 4}: Tm). The UD-170A was for dose measurement of the inner useful X-ray beams, while the UD-110S was for outer beams. The measured organ and tissue were those recommended with ICRP60 (gonad, breast, bone marrow, lung, thyroid gland, esophagus, stomach, colon, liver, bladder, skin, brain, thymus, adrenal, kidney, spleen, pancrease, upper large intestine, uterus, eyes and major salivary gland). The imaging by Orhto-CT was made in the left maxillary 1st molar, left mandibular 1st molar and temporomandibular joint. 3DX measurement was made in the maxillary incisor region and middle ear regions other than the regions mentioned above. The skin

Agreement and precision of periprosthetic bone density measurements in micro-CT, single and dual energy CT.

Science.gov (United States)

Mussmann, Bo; Overgaard, Søren; Torfing, Trine; Traise, Peter; Gerke, Oke; Andersen, Poul Erik

2017-07-01

The objective of this study was to test the precision and agreement between bone mineral density measurements performed in micro CT, single and dual energy computed tomography, to determine how the keV level influences density measurements and to assess the usefulness of quantitative dual energy computed tomography as a research tool for longitudinal studies aiming to measure bone loss adjacent to total hip replacements. Samples from 10 fresh-frozen porcine femoral heads were placed in a Perspex phantom and computed tomography was performed with two acquisition modes. Bone mineral density was calculated and compared with measurements derived from micro CT. Repeated scans and dual measurements were performed in order to measure between- and within-scan precision. Mean density difference between micro CT and single energy computed tomography was 72 mg HA/cm 3 . For dual energy CT, the mean difference at 100 keV was 128 mg HA/cm 3 while the mean difference at 110-140 keV ranged from -84 to -67 mg HA/cm 3 compared with micro CT. Rescanning the samples resulted in a non-significant overall between-scan difference of 13 mg HA/cm 3 . Bland-Altman limits of agreement were wide and intraclass correlation coefficients ranged from 0.29 to 0.72, while 95% confidence intervals covered almost the full possible range. Repeating the density measurements for within-scan precision resulted in ICCs >0.99 and narrow limits of agreement. Single and dual energy quantitative CT showed excellent within-scan precision, but poor between-scan precision. No significant density differences were found in dual energy quantitative CT at keV-levels above 110 keV. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1470-1477, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Ring artifact correction for high-resolution micro CT

International Nuclear Information System (INIS)

Kyriakou, Yiannis; Prell, Daniel; Kalender, Willi A

2009-01-01

In high-resolution micro CT using flat detectors (FD), imperfect or defect detector elements may cause concentric-ring artifacts due to their continuous over- or underestimation of attenuation values, which often disturb image quality. We here present a dedicated image-based ring artifact correction method for high-resolution micro CT, based on median filtering of the reconstructed image and working on a transformed version of the reconstructed images in polar coordinates. This post-processing method reduced ring artifacts in the reconstructed images and improved image quality for phantom and in in vivo scans. Noise and artifacts were reduced both in transversal and in multi-planar reformations along the longitudinal axis. (note)

Establishment study of the in vivo imaging analysis with small animal imaging modalities (micro-PET and micro-SPECT/CT) for bio-drug development

Energy Technology Data Exchange (ETDEWEB)

Jang, Beomsu; Park, Sanghyeon; Park, Jeonghoon; Jo, Sungkee; Jung, Uhee; Kim, Seolwha; Lee, Yunjong; Choi, Daeseong

2011-01-15

In this study, we established the image acquisition and analysis procedures of micro-PET, SPECT/CT using the experimental animal (mouse) for the development of imaging assessment method for the bio-drug. We examined the micro-SPECT/CT, PET imaging study using the Siemens Inveon micro-multimodality system (SPECT/CT) and micro-PET with {sup 99m}Tc-MDP, DMSA, and {sup 18}F-FDG. SPECT imaging studies using 3 types of pinhole collimators. 5-MWB collimator was used for SPECT image study. To study whole-body distribution, {sup 99m}Tc-MDP SPECT image study was performed. We obtained the fine distribution image. And the CT images was obtained to provide the anatomical information. And then these two types images are fused. To study specific organ uptake, we examined {sup 99}mTc-DMSA SPECT/CT imaging study. We also performed the PET image study using U87MG tumor bearing mice and {sup 18}F-FDG. The overnight fasting, warming and anesthesia with 2% isoflurane pretreatment enhance the tumor image through reducing the background uptake including brown fat, harderian gland and skeletal muscles. Also we got the governmental approval for use of x-ray generator for CT and radioisotopes as sealed and open source. We prepared the draft of process procedure for the experimental animal imaging facility. These research results can be utilized as a basic image study protocols and data for the image assessment of drugs including biological drug.

Establishment study of the in vivo imaging analysis with small animal imaging modalities (micro-PET and micro-SPECT/CT) for bio-drug development

International Nuclear Information System (INIS)

Jang, Beomsu; Park, Sanghyeon; Park, Jeonghoon; Jo, Sungkee; Jung, Uhee; Kim, Seolwha; Lee, Yunjong; Choi, Daeseong

2011-01-01

In this study, we established the image acquisition and analysis procedures of micro-PET, SPECT/CT using the experimental animal (mouse) for the development of imaging assessment method for the bio-drug. We examined the micro-SPECT/CT, PET imaging study using the Siemens Inveon micro-multimodality system (SPECT/CT) and micro-PET with 99m Tc-MDP, DMSA, and 18 F-FDG. SPECT imaging studies using 3 types of pinhole collimators. 5-MWB collimator was used for SPECT image study. To study whole-body distribution, 99m Tc-MDP SPECT image study was performed. We obtained the fine distribution image. And the CT images was obtained to provide the anatomical information. And then these two types images are fused. To study specific organ uptake, we examined 99 mTc-DMSA SPECT/CT imaging study. We also performed the PET image study using U87MG tumor bearing mice and 18 F-FDG. The overnight fasting, warming and anesthesia with 2% isoflurane pretreatment enhance the tumor image through reducing the background uptake including brown fat, harderian gland and skeletal muscles. Also we got the governmental approval for use of x-ray generator for CT and radioisotopes as sealed and open source. We prepared the draft of process procedure for the experimental animal imaging facility. These research results can be utilized as a basic image study protocols and data for the image assessment of drugs including biological drug

Benign Prostatic Hyperplasia: Cone-Beam CT in Conjunction with DSA for Identifying Prostatic Arterial Anatomy.

Science.gov (United States)

Wang, Mao Qiang; Duan, Feng; Yuan, Kai; Zhang, Guo Dong; Yan, Jieyu; Wang, Yan

2017-01-01

Purpose To describe findings in prostatic arteries (PAs) at digital subtraction angiography (DSA) and cone-beam computed tomography (CT) that allow identification of benign prostatic hyperplasia and to determine the value added with the use of cone-beam CT. Materials and Methods This retrospective single-institution study was approved by the institutional review board, and the requirement for written informed consent was waived. From February 2009 to December 2014, a total of 148 patients (mean age ± standard deviation, 70.5 years ± 14.5) underwent DSA of the internal iliac arteries and cone-beam CT with a flat-detector angiographic system before they underwent prostate artery embolization. Both the DSA and cone-beam CT images were evaluated by two interventional radiologists to determine the number of independent PAs and their origins and anastomoses with adjacent arteries. The exact McNemar test was used to compare the detection rate of the PAs and the anastomoses with DSA and with cone-beam CT. Results The PA anatomy was evaluated successfully by means of cone-beam CT in conjunction with DSA in all patients. Of the 296 pelvic sides, 274 (92.6%) had only one PA. The most frequent PA origin was the common gluteal-pudendal trunk with the superior vesicular artery in 118 (37.1%), followed by the anterior division of the internal iliac artery in 99 (31.1%), and the internal pudendal artery in 77 (24.2%) pelvic sides. In 67 (22.6%) pelvic sides, anastomoses to adjacent arteries were documented. The numbers of PA origins and anastomoses, respectively, that could be identified were significantly higher with cone-beam CT (301 of 318 [94.7%] and 65 of 67 [97.0%]) than with DSA (237 [74.5%] and 39 [58.2%], P < .05). Cone-beam CT provided essential information that was not available with DSA in 90 of 148 (60.8%) patients. Conclusion Cone-beam CT is a useful adjunctive technique to DSA for identification of the PA anatomy and provides information to help treatment planning

[Detection of marginal leakage of Class V restorations in vitro by micro-CT].

Science.gov (United States)

Gu, Lin-juan; Zhao, Xin-yi; Li, Shi-bao

2012-09-01

To evaluate the reliability and superiority of micro-CT in marginal leakage assessment of Class V restorations. Class V preparations with gingival margins in dentin and occlusal in enamel were made in sixteen extracted non-carious human molars and restored with dental bonding agents and composite resin. All teeth were then immersed in 50% ammonia-silver nitrate solution for 12 hours, followed by developing solution for 8 hours. Each restoration was scanned by a micro-CT and silver leakage was measured and three-dimensional image of the silver leakage alone cavity wall were reconstructed. Afterward, all restorations were sectioned and examined for leakage depth using a microscope. The silver leakage depth of each restoration obtained by micro-CT and microscope were compared for equivalency. The silver leakage depths in gingival wall obtained with micro-CT (0.78 mm) and microscope (0.74 mm) showed no significant difference (P > 0.05), while the judgment of leakage depths in occlusal wall in micro-CT image (0.40 mm) was affected by adjacent enamel structure, giving less leakage depths compared to microscope (0.72 mm)(P leakages showed channels on their way to spreading. Micro-CT can detect precisely the silver leakage in the dentin wall of a restoration and display its three-dimensional shape fully. Enamel structure affects the detection of the silver leakage next to it.

Evaluation of the OSC-TV iterative reconstruction algorithm for cone-beam optical CT.

Science.gov (United States)

Matenine, Dmitri; Mascolo-Fortin, Julia; Goussard, Yves; Després, Philippe

2015-11-01

The present work evaluates an iterative reconstruction approach, namely, the ordered subsets convex (OSC) algorithm with regularization via total variation (TV) minimization in the field of cone-beam optical computed tomography (optical CT). One of the uses of optical CT is gel-based 3D dosimetry for radiation therapy, where it is employed to map dose distributions in radiosensitive gels. Model-based iterative reconstruction may improve optical CT image quality and contribute to a wider use of optical CT in clinical gel dosimetry. This algorithm was evaluated using experimental data acquired by a cone-beam optical CT system, as well as complementary numerical simulations. A fast GPU implementation of OSC-TV was used to achieve reconstruction times comparable to those of conventional filtered backprojection. Images obtained via OSC-TV were compared with the corresponding filtered backprojections. Spatial resolution and uniformity phantoms were scanned and respective reconstructions were subject to evaluation of the modulation transfer function, image uniformity, and accuracy. The artifacts due to refraction and total signal loss from opaque objects were also studied. The cone-beam optical CT data reconstructions showed that OSC-TV outperforms filtered backprojection in terms of image quality, thanks to a model-based simulation of the photon attenuation process. It was shown to significantly improve the image spatial resolution and reduce image noise. The accuracy of the estimation of linear attenuation coefficients remained similar to that obtained via filtered backprojection. Certain image artifacts due to opaque objects were reduced. Nevertheless, the common artifact due to the gel container walls could not be eliminated. The use of iterative reconstruction improves cone-beam optical CT image quality in many ways. The comparisons between OSC-TV and filtered backprojection presented in this paper demonstrate that OSC-TV can potentially improve the rendering of

Serial CT Findings of Paragonimus Infested Dogs and the Micro-CT Findings of the Worm Cysts

International Nuclear Information System (INIS)

Lee, Chang Hyun; Im, Jung Gi; Goo, Jin Mo; Lee, Hyun Ju; Hong, Sung Tae; Shen, Cheng Hua; Chung, Doo Hyun; Son, Kyu Ri; Chang, Jung Min; Eo, Hong

2007-01-01

To investigate the serial CT findings of Paragonimus westermani infected dogs and the microscopic structures of the worm cysts using Micro-CT. This study was approved by the committee on animal research at our institution. Fifteen dogs infected with P. westermani underwent serial contrast-enhanced CT scans at pre-infection, after 10 days of infection, and monthly thereafter until six months for determining the radiologic-pathologic correlation. Three dogs (one dog each time) were sacrificed at 1, 3 and 6 months, respectively. After fixation of the lungs, both multi-detector CT and Micro-CT were performed for examining the worm cysts. The initial findings were pleural effusion and/or subpleural groundglass opacities or linear opacities at day 10. At day 30, subpleural and peribronchial nodules appeared with hydropneumothorax and abdominal or chest wall air bubbles. Cavitary change and bronchial dilatation began to be seen on CT scan at day 30 and this was mostly seen together with mediastinal lymphadenopathy at day 60. Thereafter, subpleural ground-glass opacities and nodules with or without cavitary changes were persistently observed until day 180. After cavitary change of the nodules, the migratory features of the subpleural or peribronchial nodules were seen on all the serial CT scans. Micro-CT showed that the cyst wall contained dilated interconnected tubular structures, which had communications with the cavity and the adjacent distal bronchus. The CT findings of paragonimiasis depend on the migratory stage of the worms. The worm cyst can have numerous interconnected tubular channels within its own wall and these channels have connections with the cavity and the adjacent distal bronchus

Imaging study of pancreatic ductal adenocarcinomas in Syrian hamsters using X-ray micro-computed tomography (CT)

International Nuclear Information System (INIS)

Kitahashi, Tsukasa; Mutoh, Michihiro; Tsurusaki, Masakatsu

2010-01-01

X-ray computed tomography (CT) has been used for diagnoses of human pancreatic cancer. Although micro-CT is a useful approach to evaluate macromorphology of organs/tissue also in animal models, reports on pancreatic tumors are limited. In this study, the utility of micro-CT was assessed in characterizing chemically induced pancreatic tumors in Syrian hamsters. Hamsters treated with or without N-nitrosobis(2-oxopropyl)amine (BOP) were injected with the antispasmodic agent, scopolamine butylbromide, and contrast agents, 5 or 10 mL/kg body weight of iopamidol or Fenestra VC at 18-38 weeks, then examined by micro-CT scanning with a respiratory gating system. Both peristaltic and respiratory movements were substantially suppressed by the combination of scopolamine butylbromide treatment and the respiratory gating system, resulting in improvements of image qualities. Iopamidol clearly visualized the pancreatic parenchyma and contrasted the margins among the pancreas and other abdominal organs/tissue. Meanwhile Fenestra VC predominantly contrasted abdominal vascular systems, but the margins among pancreas and other organs/tissue remained obscure. Six pancreatic tumors of 4-13 mm in diameter were detected in four of 15 animals, but not the five tumors of 1-4 mm in diameter. The inner tumor images were heterogeneously or uniformly visualized by iopamidol and Fenestra VC. Overall, iopamidol could clearly contrast between pancreatic parenchyma and the tumors as compared with Fenestra VC. All tumors confirmed were histopathologically diagnosed as pancreatic ductal adenocarcinomas. Thus, micro-CT could be useful to evaluate the carcinogenic processes and preventive methods of pancreatic cancer in hamsters and to assess the novel contrast agents for detection of small pancreatic cancer in humans. (author)

Micro-patterns fabrication using focused proton beam lithography

Energy Technology Data Exchange (ETDEWEB)

Cutroneo, M., E-mail: cutroneo@ujf.cas.cz [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic); Havranek, V. [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic); Mackova, A. [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic); Department of Physics, Faculty of Science, J.E. Purkinje University, Ceske mladeze 8, 400 96 Usti nad Labem (Czech Republic); Semian, V. [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic); Torrisi, L. [Department of Physics and Earth Sciences, Messina University, V.le F.S. d’Alcontres 31, 98166 S. Agata, Messina (Italy); Calcagno, L. [Department of Physics, Catania University, V. S. Sofia 64, 95123 Catania (Italy)

2016-03-15

Proton beam writing technique was recently introduced at 3MV Tandetron accelerator at Nuclear Physics Institute in Rez (Czech Republic). It has been used, to produce three-dimensional (3D) micro-structures in poly(methylmethacrylate) by 2.0 MeV and 2.6 MeV protons micro-beam. Micro-channels (52 μm × 52 μm) have been realized. After chemical etching, the quality of the bottom and side walls of the produced structures in PMMA were analyzed using Scanning Transmission Ion Microscopy (STIM).

Ambient radiation levels in a microPET/CT research laboratory

Energy Technology Data Exchange (ETDEWEB)

Sarmento, D.M.; Rodrigues, D.L.; Sanches, M.P.; Carneiro, J.C.G.G., E-mail: janetegc@ipen.br [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

This study focuses on initial radiological evaluation and the exposure situation related to the worker task in a micro-positron emission tomography/computed tomography laboratory (microPET/CT). Selected and calibrated thermoluminescent dosimeters, TLD, of CaSO{sub 4}:Dy were used to measure room radiation levels. The detectors were placed in several selected points inside the microPET/CT laboratory and adjacent rooms. In addition, the occupationally exposed workers were monthly evaluated for external and internal exposures. In none of the selected points the dose values exceeded the radiation dose limit established for supervised area, as well as the values obtained in individual monitoring. (author)

Ambient radiation levels in a microPET/CT research laboratory

International Nuclear Information System (INIS)

Sarmento, D.M.; Rodrigues, D.L.; Sanches, M.P.; Carneiro, J.C.G.G.

2015-01-01

This study focuses on initial radiological evaluation and the exposure situation related to the worker task in a micro-positron emission tomography/computed tomography laboratory (microPET/CT). Selected and calibrated thermoluminescent dosimeters, TLD, of CaSO 4 :Dy were used to measure room radiation levels. The detectors were placed in several selected points inside the microPET/CT laboratory and adjacent rooms. In addition, the occupationally exposed workers were monthly evaluated for external and internal exposures. In none of the selected points the dose values exceeded the radiation dose limit established for supervised area, as well as the values obtained in individual monitoring. (author)

Estimation of skull table thickness with clinical CT and validation with microCT.

Science.gov (United States)

Lillie, Elizabeth M; Urban, Jillian E; Weaver, Ashley A; Powers, Alexander K; Stitzel, Joel D

2015-01-01

Brain injuries resulting from motor vehicle crashes (MVC) are extremely common yet the details of the mechanism of injury remain to be well characterized. Skull deformation is believed to be a contributing factor to some types of traumatic brain injury (TBI). Understanding biomechanical contributors to skull deformation would provide further insight into the mechanism of head injury resulting from blunt trauma. In particular, skull thickness is thought be a very important factor governing deformation of the skull and its propensity for fracture. Current computed tomography (CT) technology is limited in its ability to accurately measure cortical thickness using standard techniques. A method to evaluate cortical thickness using cortical density measured from CT data has been developed previously. This effort validates this technique for measurement of skull table thickness in clinical head CT scans using two postmortem human specimens. Bone samples were harvested from the skulls of two cadavers and scanned with microCT to evaluate the accuracy of the estimated cortical thickness measured from clinical CT. Clinical scans were collected at 0.488 and 0.625 mm in plane resolution with 0.625 mm thickness. The overall cortical thickness error was determined to be 0.078 ± 0.58 mm for cortical samples thinner than 4 mm. It was determined that 91.3% of these differences fell within the scanner resolution. Color maps of clinical CT thickness estimations are comparable to color maps of microCT thickness measurements, indicating good quantitative agreement. These data confirm that the cortical density algorithm successfully estimates skull table thickness from clinical CT scans. The application of this technique to clinical CT scans enables evaluation of cortical thickness in population-based studies. © 2014 Anatomical Society.

Single-slice rebinning method for helical cone-beam CT

International Nuclear Information System (INIS)

Noo, F.; Defrise, M.; Clackdoyle, R.

1999-01-01

In this paper, we present reconstruction results from helical cone-beam CT data, obtained using a simple and fast algorithm, which we call the CB-SSRB algorithm. This algorithm combines the single-slice rebinning method of PET imaging with the weighting schemes of spiral CT algorithms. The reconstruction is approximate but can be performed using 2D multislice fan-beam filtered backprojection. The quality of the results is surprisingly good, and far exceeds what one might expect, even when the pitch of the helix is large. In particular, with this algorithm comparable quality is obtained using helical cone-beam data with a normalized pitch of 10 to that obtained using standard spiral CT reconstruction with a normalized pitch of 2. (author)

Multistable wireless micro-actuator based on antagonistic pre-shaped double beams

International Nuclear Information System (INIS)

Liu, X; Lamarque, F; Doré, E; Pouille, P

2015-01-01

This paper presents a monolithic multistable micro-actuator based on antagonistic pre-shaped double beams. The designed micro-actuator is formed by two rows of bistable micro-actuators providing four stable positions. The bistable mechanism for each row is a pair of antagonistic pre-shaped beams. This bistable mechanism has an easier pre-load operation compared to the pre-compressed bistable beams method. Furthermore, it solves the asymmetrical force output problem of parallel pre-shaped bistable double beams. At the same time, the geometrical limit is lower than parallel pre-shaped bistable double beams, which ensures a smaller stroke of the micro-actuator with the same dimensions. The designed micro-actuator is fabricated using laser cutting machine on medium density fiberboard (MDF). The bistability and merits of antagonistic pre-shaped double beams are experimentally validated. Finally, a contactless actuation test is performed using 660 nm wavelength laser heating shape memory alloy (SMA) active elements. (paper)

Multistable wireless micro-actuator based on antagonistic pre-shaped double beams

Science.gov (United States)

Liu, X.; Lamarque, F.; Doré, E.; Pouille, P.

2015-07-01

This paper presents a monolithic multistable micro-actuator based on antagonistic pre-shaped double beams. The designed micro-actuator is formed by two rows of bistable micro-actuators providing four stable positions. The bistable mechanism for each row is a pair of antagonistic pre-shaped beams. This bistable mechanism has an easier pre-load operation compared to the pre-compressed bistable beams method. Furthermore, it solves the asymmetrical force output problem of parallel pre-shaped bistable double beams. At the same time, the geometrical limit is lower than parallel pre-shaped bistable double beams, which ensures a smaller stroke of the micro-actuator with the same dimensions. The designed micro-actuator is fabricated using laser cutting machine on medium density fiberboard (MDF). The bistability and merits of antagonistic pre-shaped double beams are experimentally validated. Finally, a contactless actuation test is performed using 660 nm wavelength laser heating shape memory alloy (SMA) active elements.

Point spread function modeling and image restoration for cone-beam CT

International Nuclear Information System (INIS)

Zhang Hua; Shi Yikai; Huang Kuidong; Xu Zhe

2015-01-01

X-ray cone-beam computed tomography (CT) has such notable features as high efficiency and precision, and is widely used in the fields of medical imaging and industrial non-destructive testing, but the inherent imaging degradation reduces the quality of CT images. Aimed at the problems of projection image degradation and restoration in cone-beam CT, a point spread function (PSF) modeling method is proposed first. The general PSF model of cone-beam CT is established, and based on it, the PSF under arbitrary scanning conditions can be calculated directly for projection image restoration without the additional measurement, which greatly improved the application convenience of cone-beam CT. Secondly, a projection image restoration algorithm based on pre-filtering and pre-segmentation is proposed, which can make the edge contours in projection images and slice images clearer after restoration, and control the noise in the equivalent level to the original images. Finally, the experiments verified the feasibility and effectiveness of the proposed methods. (authors)

Cone-Beam CT with Flat-Panel-Detector Digital Angiography System: Early Experience in Abdominal Interventional Procedures

International Nuclear Information System (INIS)

Hirota, Shozo; Nakao, Norio; Yamamoto, Satoshi; Kobayashi, Kaoru; Maeda, Hiroaki; Ishikura, Reiichi; Miura, Koui; Sakamoto, Kiyoshi; Ueda, Ken; Baba, Rika

2006-01-01

We developed a cone-beam computed tomography (CBCT) system equipped with a large flat-panel detector. Data obtained by 200 o rotation imaging are reconstructed by means of CBCT to generate three-dimensional images. We report the use of CBCT angiography using CBCT in 10 patients with 8 liver malignancies and 2 hypersplenisms during abdominal interventional procedures. CBCT was very useful for interventional radiologists to confirm a perfusion area of the artery catheter wedged on CT by injection of contrast media through the catheter tip, although the image quality was slightly degraded, scoring as 2.60 on average by streak artifacts. CBCT is space-saving because it does not require a CT system with a gantry, and it is also time-saving because it does not require the transfer of patients

A reconstruction method for cone-beam differential x-ray phase-contrast computed tomography.

Science.gov (United States)

Fu, Jian; Velroyen, Astrid; Tan, Renbo; Zhang, Junwei; Chen, Liyuan; Tapfer, Arne; Bech, Martin; Pfeiffer, Franz

2012-09-10

Most existing differential phase-contrast computed tomography (DPC-CT) approaches are based on three kinds of scanning geometries, described by parallel-beam, fan-beam and cone-beam. Due to the potential of compact imaging systems with magnified spatial resolution, cone-beam DPC-CT has attracted significant interest. In this paper, we report a reconstruction method based on a back-projection filtration (BPF) algorithm for cone-beam DPC-CT. Due to the differential nature of phase contrast projections, the algorithm restrains from differentiation of the projection data prior to back-projection, unlike BPF algorithms commonly used for absorption-based CT data. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a micro-focus x-ray tube source. Moreover, the numerical simulation and experimental results demonstrate that the proposed method can deal with several classes of truncated cone-beam datasets. We believe that this feature is of particular interest for future medical cone-beam phase-contrast CT imaging applications.

Prototype heel effect compensation filter for cone-beam CT

International Nuclear Information System (INIS)

Mori, Shinichiro; Endo, Masahiro; Nishizawa, Kanae; Ohno, Mari; Miyazaki, Hiroaki; Tsujita, Kazuhiko; Saito, Yasuo

2005-01-01

The prototype cone-beam CT (CBCT) has a larger beam width than the conventional multi-detector row CT (MDCT). This causes a non-uniform angular distribution of the x-ray beam intensity known as the heel effect. Scan conditions for CBCT tube current are adjusted on the anode side to obtain an acceptable clinical image quality. However, as the dose is greater on the cathode side than on the anode side, the signal-to-noise ratio on the cathode side is excessively high, resulting in an unnecessary dose amount. To compensate for the heel effect, we developed a heel effect compensation (HEC) filter. The HEC filter rendered the dose distribution uniform and reduced the dose by an average of 25% for free air and by 20% for CTDI phantoms compared to doses with the conventional filter. In addition, its effect in rendering the effective energy uniform resulted in an improvement in image quality. This new HEC filter may be useful in cone-beam CT studies. (note)

Four-dimensional cone beam CT with adaptive gantry rotation and adaptive data sampling

International Nuclear Information System (INIS)

Lu Jun; Guerrero, Thomas M.; Munro, Peter; Jeung, Andrew; Chi, P.-C. M.; Balter, Peter; Zhu, X. Ronald; Mohan, Radhe; Pan Tinsu

2007-01-01

We have developed a new four-dimensional cone beam CT (4D-CBCT) on a Varian image-guided radiation therapy system, which has radiation therapy treatment and cone beam CT imaging capabilities. We adapted the speed of gantry rotation time of the CBCT to the average breath cycle of the patient to maintain the same level of image quality and adjusted the data sampling frequency to keep a similar level of radiation exposure to the patient. Our design utilized the real-time positioning and monitoring system to record the respiratory signal of the patient during the acquisition of the CBCT data. We used the full-fan bowtie filter during data acquisition, acquired the projection data over 200 deg of gantry rotation, and reconstructed the images with a half-scan cone beam reconstruction. The scan time for a 200-deg gantry rotation per patient ranged from 3.3 to 6.6 min for the average breath cycle of 3-6 s. The radiation dose of the 4D-CBCT was about 1-2 times the radiation dose of the 4D-CT on a multislice CT scanner. We evaluated the 4D-CBCT in scanning, data processing and image quality with phantom studies. We demonstrated the clinical applicability of the 4D-CBCT and compared the 4D-CBCT and the 4D-CT scans in four patient studies. The contrast-to-noise ratio of the 4D-CT was 2.8-3.5 times of the contrast-to-noise ratio of the 4D-CBCT in the four patient studies

Modeling and Reconstruction of Micro-structured 3D Chitosan/Gelatin Porous Scaffolds Using Micro-CT

Science.gov (United States)

Gong, Haibo; Li, Dichen; He, Jiankang; Liu, Yaxiong; Lian, Qin; Zhao, Jinna

2008-09-01

Three dimensional (3D) channel networks are the key to promise the uniform distribution of nutrients inside 3D hepatic tissue engineering scaffolds and prompt elimination of metabolic products out of the scaffolds. 3D chitosan/gelatin porous scaffolds with predefined internal channels were fabricated and a combination of light microscope, laser confocal microscopy and micro-CT were employed to characterize the structure of porous scaffolds. In order to evaluate the flow field distribution inside the micro-structured 3D scaffolds, a computer reconstructing method based on Micro-CT was proposed. According to this evaluating method, a contrast between 3D porous scaffolds with and without predefined internal channels was also performed to assess scaffolds' fluid characters. Results showed that the internal channel of the 3D scaffolds formed the 3D fluid channel network; the uniformity of flow field distribution of the scaffolds fabricated in this paper was better than the simple porous scaffold without micro-fluid channels.

4-D Micro-CT of the Mouse Heart

Directory of Open Access Journals (Sweden)

Cristian T. Badea

2005-04-01

Full Text Available Purpose: Demonstrate noninvasive imaging methods for in vivo characterization of cardiac structure and function in mice using a micro-CT system that provides high photon fluence rate and integrated motion control. Materials and Methods: Simultaneous cardiac- and respiratory-gated micro-CT was performed in C57BL/6 mice during constant intravenous infusion of a conventional iodinated contrast agent (Isovue-370, and after a single intravenous injection of a blood pool contrast agent (Fenestra VC. Multiple phases of the cardiac cycle were reconstructed with contrast to noise and spatial resolution sufficient for quantitative assessment of cardiac function. Results: Contrast enhancement with Isovue-370 increased over time with a maximum of ~500 HU (aorta and 900 HU (kidney cortex. Fenestra VC provided more constant enhancement over 3 hr, with maximum enhancement of ~620 HU (aorta and ~90 HU (kidney cortex. The maximum enhancement difference between blood and myocardium in the heart was ~250 HU for Isovue-370 and ~500 HU for Fenestra VC. In mice with Fenestra VC, volumetric measurements of the left ventricle were performed and cardiac function was estimated by ejection fraction, stroke volume, and cardiac output. Conclusion: Image quality with Fenestra VC was sufficient for morphological and functional studies required for a standardized method of cardiac phenotyping of the mouse.

Radiological control of a microPET/CT laboratory

International Nuclear Information System (INIS)

Sarmento, Daniele M.; Sanches, Matias P.; Carneiro, Janete C.G.G.

2015-01-01

This paper presents the radiological control of a research laboratory in order to satisfy national standards and international recommendations. The microPET/CT laboratory in IPEN uses an Albira system for research purposes in small animals. This study focuses mainly to carry out an initial radiological evaluation and the exposure situation related with the task. The assessment of workplace conditions and individual exposures constitutes as integral part of the operational monitoring programme. Initially, the radiometric survey in laboratory has been carried out using an ionization chamber Radcal 9010 (10 x 5 - 1800). In addition, nine monitoring points with potential exposure were selected, where thermoluminescent dosimeters, TLDs, of CaSO 4 :Dy, were positioned. The occupationally exposed workers were monthly evaluated for external exposures using TL dosimeters, worn on the surface of the body. For internal exposure, the evaluated period was approximately one year starting on April 2014. The average effective dose of the occupationally exposed workers did not exceed 2.4 mSv in the year of 2014, which is equal to the recording level. The workplace, microPET/CT laboratory, is classified as supervised area and the monitoring results in the evaluated period, are within the dose limits established by national standard, as well as the values obtained in individual control. (author)

Radiological control of a microPET/CT laboratory

Energy Technology Data Exchange (ETDEWEB)

Sarmento, Daniele M.; Sanches, Matias P.; Carneiro, Janete C.G.G., E-mail: dms.danica@gmail.com.br, E-mail: msanches@ipen.br, E-mail: janetgc@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

This paper presents the radiological control of a research laboratory in order to satisfy national standards and international recommendations. The microPET/CT laboratory in IPEN uses an Albira system for research purposes in small animals. This study focuses mainly to carry out an initial radiological evaluation and the exposure situation related with the task. The assessment of workplace conditions and individual exposures constitutes as integral part of the operational monitoring programme. Initially, the radiometric survey in laboratory has been carried out using an ionization chamber Radcal 9010 (10 x 5 - 1800). In addition, nine monitoring points with potential exposure were selected, where thermoluminescent dosimeters, TLDs, of CaSO{sub 4}:Dy, were positioned. The occupationally exposed workers were monthly evaluated for external exposures using TL dosimeters, worn on the surface of the body. For internal exposure, the evaluated period was approximately one year starting on April 2014. The average effective dose of the occupationally exposed workers did not exceed 2.4 mSv in the year of 2014, which is equal to the recording level. The workplace, microPET/CT laboratory, is classified as supervised area and the monitoring results in the evaluated period, are within the dose limits established by national standard, as well as the values obtained in individual control. (author)

Integration of PET-CT and cone-beam CT for image-guided radiotherapy with high image quality and registration accuracy

Science.gov (United States)

Wu, T.-H.; Liang, C.-H.; Wu, J.-K.; Lien, C.-Y.; Yang, B.-H.; Huang, Y.-H.; Lee, J. J. S.

2009-07-01

Hybrid positron emission tomography-computed tomography (PET-CT) system enhances better differentiation of tissue uptake of 18F-fluorodeoxyglucose (18F-FDG) and provides much more diagnostic value in the non-small-cell lung cancer and nasopharyngeal carcinoma (NPC). In PET-CT, high quality CT images not only offer diagnostic value on anatomic delineation of the tissues but also shorten the acquisition time for attenuation correction (AC) compared with PET-alone imaging. The linear accelerators equipped with the X-ray cone-beam computed tomography (CBCT) imaging system for image-guided radiotherapy (IGRT) provides excellent verification on position setup error. The purposes of our study were to optimize the CT acquisition protocols of PET-CT and to integrate the PET-CT and CBCT for IGRT. The CT imaging parameters were modified in PET-CT for increasing the image quality in order to enhance the diagnostic value on tumour delineation. Reproducibility and registration accuracy via bone co-registration algorithm between the PET-CT and CBCT were evaluated by using a head phantom to simulate a head and neck treatment condition. Dose measurement in computed tomography dose index (CTDI) was also estimated. Optimization of the CT acquisition protocols of PET-CT was feasible in this study. Co-registration accuracy between CBCT and PET-CT on axial and helical modes was in the range of 1.06 to 2.08 and 0.99 to 2.05 mm, respectively. In our result, it revealed that the accuracy of the co-registration with CBCT on helical mode was more accurate than that on axial mode. Radiation doses in CTDI were 4.76 to 18.5 mGy and 4.83 to 18.79 mGy on axial and helical modes, respectively. Registration between PET-CT and CBCT is a state-of-the-art registration technology which could provide much information on diagnosis and accurate tumour contouring on radiotherapy while implementing radiotherapy procedures. This novelty technology of PET-CT and cone-beam CT integration for IGRT may have a

Integration of PET-CT and cone-beam CT for image-guided radiotherapy with high image quality and registration accuracy

International Nuclear Information System (INIS)

Wu, T-H; Liang, C-H; Wu, J-K; Lien, C-Y; Yang, B-H; Lee, J J S; Huang, Y-H

2009-01-01

Hybrid positron emission tomography-computed tomography (PET-CT) system enhances better differentiation of tissue uptake of 18 F-fluorodeoxyglucose ( 18 F-FDG) and provides much more diagnostic value in the non-small-cell lung cancer and nasopharyngeal carcinoma (NPC). In PET-CT, high quality CT images not only offer diagnostic value on anatomic delineation of the tissues but also shorten the acquisition time for attenuation correction (AC) compared with PET-alone imaging. The linear accelerators equipped with the X-ray cone-beam computed tomography (CBCT) imaging system for image-guided radiotherapy (IGRT) provides excellent verification on position setup error. The purposes of our study were to optimize the CT acquisition protocols of PET-CT and to integrate the PET-CT and CBCT for IGRT. The CT imaging parameters were modified in PET-CT for increasing the image quality in order to enhance the diagnostic value on tumour delineation. Reproducibility and registration accuracy via bone co-registration algorithm between the PET-CT and CBCT were evaluated by using a head phantom to simulate a head and neck treatment condition. Dose measurement in computed tomography dose index (CTDI) was also estimated. Optimization of the CT acquisition protocols of PET-CT was feasible in this study. Co-registration accuracy between CBCT and PET-CT on axial and helical modes was in the range of 1.06 to 2.08 and 0.99 to 2.05 mm, respectively. In our result, it revealed that the accuracy of the co-registration with CBCT on helical mode was more accurate than that on axial mode. Radiation doses in CTDI were 4.76 to 18.5 mGy and 4.83 to 18.79 mGy on axial and helical modes, respectively. Registration between PET-CT and CBCT is a state-of-the-art registration technology which could provide much information on diagnosis and accurate tumour contouring on radiotherapy while implementing radiotherapy procedures. This novelty technology of PET-CT and cone-beam CT integration for IGRT may have a

In-situ, real time micro-CT imaging of pore scale processes, the next frontier for laboratory based micro-CT scanning

OpenAIRE

Boone, Marijn; Bultreys, Tom; Masschaele, Bert; Van Loo, Denis; Van Hoorebeke, Luc; Cnudde, Veerle

2016-01-01

Over the past decade, laboratory based X-ray computed micro-tomography (micro-CT) has given unique insights in the internal structure of complex reservoir rocks, improving the understanding of pore scale processes and providing crucial information for pore scale modelling. Especially in-situ imaging using X-ray optimized Hassler type cells has enabled the direct visualization of fluid distributions at the pore scale under reservoir conditions. While sub-micrometre spatial resolutions are achi...

Cone-beam CT in paediatric dentistry. DIMITRA project position statement

International Nuclear Information System (INIS)

Oenning, Anne Caroline; Jacobs, Reinhilde; Pauwels, Ruben; Stratis, Andreas; Hedesiu, Mihaela; Salmon, Benjamin

2018-01-01

DIMITRA (dentomaxillofacial paediatric imaging: an investigation towards low-dose radiation induced risks) is a European multicenter and multidisciplinary project focused on optimizing cone-beam CT exposures for children and adolescents. With increasing use of cone-beam CT for dentomaxillofacial diagnostics, concern arises regarding radiation risks associated with this imaging modality, especially for children. Research evidence concerning cone-beam CT indications in children remains limited, while reports mention inconsistent recommendations for dose reduction. Furthermore, there is no paper using the combined and integrated information on the required indication-oriented image quality and the related patient dose levels. In this paper, therefore, the authors initiate an integrated approach based on current evidence regarding image quality and dose, together with the expertise of DIMITRA's members searching for a state of the art. The aim of this DIMITRA position statement is to provide indication-oriented and patient-specific recommendations regarding the main cone-beam CT applications in the pediatric field. The authors will review this position statement document when results regarding multidisciplinary approaches evolve, in a period of 5 years or earlier. (orig.)

Application of the optically stimulated luminescence (OSL) technique for mouse dosimetry in micro-CT imaging

Energy Technology Data Exchange (ETDEWEB)

Vrigneaud, Jean-Marc; Courteau, Alan; Oudot, Alexandra; Collin, Bertrand [Department of Nuclear Medicine, Centre Georges-François Leclerc, 1 rue Professeur Marion, Dijon 21079 Cedex (France); Ranouil, Julien [Landauer Europe, 33 avenue du Général Leclerc, Fontenay-aux-Roses 92266 Cedex (France); Morgand, Loïc; Raguin, Olivier [Oncodesign, 20 rue Jean Mazen, Dijon 21076 Cedex (France); Walker, Paul [LE2i CNRS UMR 5158, Faculty of Medicine, BP 87900, 21079 Dijon Cedex (France); Brunotte, François [Department of Nuclear Medicine, Centre Georges-François Leclerc, 1 rue Professeur Marion, Dijon 21079 Cedex, France and LE2i CNRS UMR 5158, Faculty of Medicine, BP 87900, 21079 Dijon Cedex (France)

2013-12-15

-like phantom. OSLDs exhibited a reproducibility of 2.4% and good linearity was found between 60 and 450 mGy. The energy scaling factor was calculated to be between 1.80 ± 0.16 and 1.86 ± 0.16, depending on protocol used. In phantoms, mean doses to tissue over a whole-body CT examination were ranging from 186.4 ± 7.6 to 234.9 ± 7.1 mGy. In mice, mean doses to tissue in the mouse trunk (thorax, abdomen, pelvis, and flanks) were between 213.0 ± 17.0 and 251.2 ± 13.4 mGy. Skin doses (3 OSLDs) were much higher with average doses between 350.6 ± 25.3 and 432.5 ± 34.1 mGy. The dose delivered during a topogram was found to be below 10 mGy. Use of the multimouse bed of the system gave a significantly 20%–40% lower dose per animal (p < 0.05).Conclusions: Absorbed doses in micro-CT were found to be relatively high. In micro-SPECT/CT imaging, the micro-CT unit is mainly used to produce a localization frame. As a result, users should pay attention to adjustable CT parameters so as to minimize the radiation dose and avoid any adverse radiation effects which may interfere with biological parameters studied.

Micro-CT of Carotid Arteries: A Tool for Experimental Studies

International Nuclear Information System (INIS)

Mohr, Andreas; Wenke, Ruediger; Roemer, Frank W.; Lynch, John A.; Gatzka, Christian; Priebe, Markus; Guermazi, Ali; Grigorian, Mikayel; Heller, Martin; Mueller-Huelsbeck, Stefan

2004-01-01

Micro-computed tomography (micro-CT) is a high-resolution, nondestructive tool for two- and three-dimensional imaging and quantification. The ability of this technique to assess atherosclerosis of the carotid artery was evaluated in three human cadaver samples based on the original axial acquisitions, multiplanar reconstructions and volume rendering techniques. Quantitative analysis included the calculation of: (1) the original lumen perimeter, original lumen area, plaque area, residual lumen area, calcified area and gross sectional area reduction of the vascular lumen from two-dimensional slices; (2) the total tissue volume, soft tissue volume and calcified tissue volume from the three-dimensional data set. This preliminary study demonstrates the potential of micro-CT as a supplementary method for the two- and three-dimensional ex vivo evaluation of carotid atherosclerosis

Cone-beam CT angiography of the thorax. An experimental study

International Nuclear Information System (INIS)

Yoshida, Katsuya; Shimada, Kazuhiro; Tadokoro, Hiroyuki

1999-01-01

The authors recently developed a cone-beam computed tomography (CT) scanner and this report presents their evaluation of its potential for thoracic vascular imaging. An X-ray tube and a video-fluoroscopic system were rotated around the objects and 360 projected images were collected in a 12-s scan. Each image was digitized and a 3 dimensional (D) image (256 x 256 x 256 voxel volume with a voxel dimension of 0.9 x 0.9 x 0.9 mm) was reconstructed. Two different 3D-CT angiographies were investigated in 2 pigs: right atriography and thoracic aortography. Each pig was anesthetized, mechanically ventilated and positioned within the scanner. Contrast agent was infused through the right atrium or the aortic root at a rate of 3 ml/s during the scan. The right atriography scan clearly delineated the anatomy of the pulmonary artery, heart chambers and thoracic aorta. The thoracic aortography scan also clearly delineated the aortic anatomy including the internal thoracic and intercostal arteries. In conclusion, cone-beam CT angiography is potentially useful for thoracic vascular imaging. (author)

The noise power spectrum in CT with direct fan beam reconstruction

International Nuclear Information System (INIS)

Baek, Jongduk; Pelc, Norbert J.

2010-01-01

The noise power spectrum (NPS) is a useful metric for understanding the noise content in images. To examine some unique properties of the NPS of fan beam CT, the authors derived an analytical expression for the NPS of fan beam CT and validated it with computer simulations. The nonstationary noise behavior of fan beam CT was examined by analyzing local regions and the entire field-of-view (FOV). This was performed for cases with uniform as well as nonuniform noise across the detector cells and across views. The simulated NPS from the entire FOV and local regions showed good agreement with the analytically derived NPS. The analysis shows that whereas the NPS of a large FOV in parallel beam CT (using a ramp filter) is proportional to frequency, the NPS with direct fan beam FBP reconstruction shows a high frequency roll off. Even in small regions, the fan beam NPS can show a sharp transition (discontinuity) at high frequencies. These effects are due to the variable magnification and therefore are more pronounced as the fan angle increases. For cases with nonuniform noise, the NPS can show the directional dependence and additional effects.

Detection of the anatomic structure and pathology in animal lung specimens: comparison of micro CT and multi-detector row CT

International Nuclear Information System (INIS)

Lim, Kun Young; Lee, Hyun Ju; Lee, Chang Hyun; Son, Kyu Ri; Goo, Jin Mo; Im, Jung Gi; Seo, Joon Beom

2006-01-01

We wanted to compare the capability of micro CT and the clinically available thin-slice multi-detector row CT (MDCT) for demonstrating fine anatomic structures and pathological lesions in formalin-fixed lung specimens. The porcine lung with shark liver oil-induced lipoid pneumonia and the canine lung with pulmonary paragonimiasis were fixed by ventilating them with formalin vapor, and they were then sliced into one-centimeter thick sections. Micro CT (section thickness, 18 micrometer) and MDCT (section thickness, 0.75 mm) images were acquired in four of the lung slices of the lipoid pneumonia specimen and in five of the lung slices of the paragonimiasis specimen. On 62 pairs of micro CT and MDCT images, 169 pairs of rectangular ROIs were manually drawn in the corresponding locations. Two chest radiologists recorded the detectability of three kinds of anatomic structures (lobular core structure, interlobular septum and small bronchiolar lumen) and two kinds of pathological lesions (ground-glass opacity and consolidation) with using a five-point scale. The statistical comparison was performed by using the Wilcoxon signed rank test. Interobserver agreement was evaluated with kappa statistics. For all observers, all the kinds of anatomic structures and pathological lesions were detected better on the micro CT images than on the MDCT images (ρ < 0.01). Agreement was fair between two observers (κ = 0.38, ρ < 0.001). The fine anatomic structures and pathological lesions of the lung were more accurately demonstrated on micro CT than on thin-slice MDCT in the inflated and fixed lung specimens

Detection of the anatomic structure and pathology in animal lung specimens: comparison of micro CT and multi-detector row CT

Energy Technology Data Exchange (ETDEWEB)

Lim, Kun Young [National Cancer Center, Goyang (Korea, Republic of); Lee, Hyun Ju; Lee, Chang Hyun; Son, Kyu Ri; Goo, Jin Mo; Im, Jung Gi [Seoul National University Hospital and the Institute of Radiation Medicine, Seoul (Korea, Republic of); Seo, Joon Beom [Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

2006-05-15

We wanted to compare the capability of micro CT and the clinically available thin-slice multi-detector row CT (MDCT) for demonstrating fine anatomic structures and pathological lesions in formalin-fixed lung specimens. The porcine lung with shark liver oil-induced lipoid pneumonia and the canine lung with pulmonary paragonimiasis were fixed by ventilating them with formalin vapor, and they were then sliced into one-centimeter thick sections. Micro CT (section thickness, 18 micrometer) and MDCT (section thickness, 0.75 mm) images were acquired in four of the lung slices of the lipoid pneumonia specimen and in five of the lung slices of the paragonimiasis specimen. On 62 pairs of micro CT and MDCT images, 169 pairs of rectangular ROIs were manually drawn in the corresponding locations. Two chest radiologists recorded the detectability of three kinds of anatomic structures (lobular core structure, interlobular septum and small bronchiolar lumen) and two kinds of pathological lesions (ground-glass opacity and consolidation) with using a five-point scale. The statistical comparison was performed by using the Wilcoxon signed rank test. Interobserver agreement was evaluated with kappa statistics. For all observers, all the kinds of anatomic structures and pathological lesions were detected better on the micro CT images than on the MDCT images ({rho} < 0.01). Agreement was fair between two observers ({kappa} = 0.38, {rho} < 0.001). The fine anatomic structures and pathological lesions of the lung were more accurately demonstrated on micro CT than on thin-slice MDCT in the inflated and fixed lung specimens.

Comparison of CT numbers between cone-beam CT and multi-detector CT

International Nuclear Information System (INIS)

Kim, Dong Soo; Han, Won Jeong; Kim, Eun Kyung

2010-01-01

To compare the CT numbers on 3 cone-beam CT (CBCT) images with those on multi-detector CT (MDCT) image using CT phantom and to develop linear regressive equations using CT numbers to material density for all the CT scanner each. Mini CT phantom comprised of five 1 inch thick cylindrical models with 1.125 inches diameter of materials with different densities (polyethylene, polystyrene, plastic water, nylon and acrylic) was used. It was scanned in 3 CBCTs (i-CAT, Alphard VEGA, Implagraphy SC) and 1 MDCT (Somatom Emotion). The images were saved as DICOM format and CT numbers were measured using OnDemand 3D. CT numbers obtained from CBCTs and MDCT images were compared and linear regression analysis was performed for the density, ρ(g/cm 3 ), as the dependent variable in terms of the CT numbers obtained from CBCTs and MDCT images. CT numbers on i-CAT and Implagraphy CBCT images were smaller than those on Somatom Emotion MDCT image (p<0.05). Linear relationship on a range of materials used for this study were ρ=0.001 H+1.07 with R2 value of 0.999 for Somatom Emotion, ρ=0.002 H+1.09 with R2 value of 0.991 for Alphard VEGA, ρ=0.001 H+1.43 with R2 value of 0.980 for i-CAT and ρ=0.001 H+1.30 with R2 value of 0.975 for Implagraphy. CT numbers on i-CAT and Implagraphy CBCT images were not same as those on Somatom Emotion MDCT image. The linear regressive equations to determine the density from the CT numbers with very high correlation coefficient were obtained on three CBCT and MDCT scan.

Comparison of CT numbers between cone-beam CT and multi-detector CT

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Soo; Han, Won Jeong; Kim, Eun Kyung [Department of Oral and Maxillofacial Radiology, School of Dentistry, Dankook University, Cheonan (Korea, Republic of)

2010-06-15

To compare the CT numbers on 3 cone-beam CT (CBCT) images with those on multi-detector CT (MDCT) image using CT phantom and to develop linear regressive equations using CT numbers to material density for all the CT scanner each. Mini CT phantom comprised of five 1 inch thick cylindrical models with 1.125 inches diameter of materials with different densities (polyethylene, polystyrene, plastic water, nylon and acrylic) was used. It was scanned in 3 CBCTs (i-CAT, Alphard VEGA, Implagraphy SC) and 1 MDCT (Somatom Emotion). The images were saved as DICOM format and CT numbers were measured using OnDemand 3D. CT numbers obtained from CBCTs and MDCT images were compared and linear regression analysis was performed for the density, {rho}(g/cm{sup 3}), as the dependent variable in terms of the CT numbers obtained from CBCTs and MDCT images. CT numbers on i-CAT and Implagraphy CBCT images were smaller than those on Somatom Emotion MDCT image (p<0.05). Linear relationship on a range of materials used for this study were {rho}=0.001 H+1.07 with R2 value of 0.999 for Somatom Emotion, {rho}=0.002 H+1.09 with R2 value of 0.991 for Alphard VEGA, {rho}=0.001 H+1.43 with R2 value of 0.980 for i-CAT and {rho}=0.001 H+1.30 with R2 value of 0.975 for Implagraphy. CT numbers on i-CAT and Implagraphy CBCT images were not same as those on Somatom Emotion MDCT image. The linear regressive equations to determine the density from the CT numbers with very high correlation coefficient were obtained on three CBCT and MDCT scan.

Evaluation of tilted cone-beam CT orbits in the development of a dedicated hybrid mammotomograph

International Nuclear Information System (INIS)

Madhav, P; Crotty, D J; Tornai, M P; McKinley, R L

2009-01-01

A compact dedicated 3D breast SPECT-CT (mammotomography) system is currently under development. In its initial prototype, the cone-beam CT sub-system is restricted to a fixed-tilt circular rotation around the patient's pendant breast. This study evaluated stationary-tilt angles for the CT sub-system that will enable maximal volumetric sampling and viewing of the breast and chest wall. Images of geometric/anthropomorphic phantoms were acquired using various fixed-tilt circular and 3D sinusoidal trajectories. The iteratively reconstructed images showed more distortion and attenuation coefficient inaccuracy from tilted cone-beam orbits than from the complex trajectory. Additionally, line profiles illustrated cupping artifacts in planes distal to the central plane of the tilted cone-beam, otherwise not apparent for images acquired with complex trajectories. This indicates that undersampled cone-beam data may be an additional cause of cupping artifacts. High-frequency objects could be distinguished for all trajectories, but their shapes and locations were corrupted by out-of-plane frequency information. Although more acrylic balls were visualized with a fixed-tilt and nearly flat cone-beam at the posterior of the breast, 3D complex trajectories have less distortion and more complete sampling throughout the reconstruction volume. While complex trajectories would ideally be preferred, negatively fixed-tilt source-detector configuration demonstrates minimally distorted patient images.

Use of cone-beam CT and live 3-D needle guidance to facilitate percutaneous nephrostomy and nephrolithotripsy access in children and adolescents

Energy Technology Data Exchange (ETDEWEB)

Hawkins, C.M. [Emory University School of Medicine, Department of Radiology and Imaging Sciences, Atlanta, GA (United States); Kukreja, Kamlesh [Texas Children' s Hospital, Department of Radiology, Houston, TX (United States); Singewald, Timothy; Johnson, Neil D.; Racadio, John M. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Minevich, Eugene; Reddy, Pramod [Cincinnati Children' s Hospital Medical Center, Department of Urology, Cincinnati, OH (United States)

2016-04-15

Gaining access into non-dilated renal collecting systems for percutaneous nephrolithotripsy, particularly in patients with prohibitive body habitus and/or scoliosis, is often challenging using conventional techniques. To evaluate the feasibility of cone-beam CT for percutaneous nephrostomy placement for subsequent percutaneous nephrolithotripsy in children and adolescents. A retrospective review of percutaneous nephrostomy revealed use of cone-beam CT and 3-D guidance in 12 percutaneous nephrostomy procedures for 9 patients between 2006 and 2015. All cone-beam CT-guided percutaneous nephrostomies were for pre-lithotripsy access and all 12 were placed in non-dilated collecting systems. Technical success was 100%. There were no complications. Cone-beam CT with 3-D guidance is a technically feasible technique for percutaneous nephrostomy in children and adolescents, specifically for nephrolithotripsy access in non-dilated collecting systems. (orig.)

Quantitative Analysis of Micro-CT Imaging and Histopathological Signatures of Experimental Arthritis in Rats

Directory of Open Access Journals (Sweden)

Matthew D. Silva

2004-10-01

Full Text Available Micro-computed tomographic (micro-CT imaging provides a unique opportunity to capture 3-D architectural information in bone samples. In this study of pathological joint changes in a rat model of adjuvant-induced arthritis (AA, quantitative analysis of bone volume and roughness were performed by micro-CT imaging and compared with histopathology methods and paw swelling measurement. Micro-CT imaging of excised rat hind paws (n = 10 stored in formalin consisted of approximately 600 30-μm slices acquired on a 512 × 512 image matrix with isotropic resolution. Following imaging, the joints were scored from H&E stained sections for cartilage/bone erosion, pannus development, inflammation, and synovial hyperplasia. From micro-CT images, quantitative analysis of absolute bone volumes and bone roughness was performed. Bone erosion in the rat AA model is substantial, leading to a significant decline in tarsal volume (27%. The result of the custom bone roughness measurement indicated a 55% increase in surface roughness. Histological and paw volume analyses also demonstrated severe arthritic disease as compared to controls. Statistical analyses indicate correlations among bone volume, roughness, histology, and paw volume. These data demonstrate that the destructive progression of disease in a rat AA model can be quantified using 3-D micro-CT image analysis, which allows assessment of arthritic disease status and efficacy of experimental therapeutic agents.

Dental imaging using laminar optical tomography and micro CT

Science.gov (United States)

Long, Feixiao; Ozturk, Mehmet S.; Intes, Xavier; Kotha, Shiva

2014-02-01

Dental lesions located in the pulp are quite difficult to identify based on anatomical contrast, and, hence, to diagnose using traditional imaging methods such as dental CT. However, such lesions could lead to functional and/or molecular optical contrast. Herein, we report on the preliminary investigation of using Laminar Optical Tomography (LOT) to image the pulp and root canals in teeth. LOT is a non-contact, high resolution, molecular and functional mesoscopic optical imaging modality. To investigate the potential of LOT for dental imaging, we injected an optical dye into ex vivo teeth samples and imaged them using LOT and micro-CT simultaneously. A rigid image registration between the LOT and micro-CT reconstruction was obtained, validating the potential of LOT to image molecular optical contrast deep in the teeth with accuracy, non-invasively. We demonstrate that LOT can retrieve the 3D bio-distribution of molecular probes at depths up to 2mm with a resolution of several hundred microns in teeth.

In vivo longitudinal micro-CT study of bent long limb bones in rat offspring.

Science.gov (United States)

De Schaepdrijver, Luc; Delille, Peter; Geys, Helena; Boehringer-Shahidi, Christian; Vanhove, Christian

2014-07-01

Micro-computed X-ray tomography (micro-CT) has been reported as a reliable method to assess ex vivo rat and rabbit fetal skeletons in embryo-fetal developmental toxicity studies. Since micro-CT is a non-invasive imaging modality it has the potential for longitudinal, in vivo investigation of postnatal skeletal development. This is the first paper using micro-CT to assess the reversibility of drug-induced bent long bones in a longitudinal study from birth to early adulthood in rat offspring. Analysis of the scans obtained on postnatal Day 0, 7, 21 and 80 showed complete recovery or repair of the bent long limb bones (including the scapula) within the first 3 weeks. When assessing risk the ability to demonstrate recovery is highly advantageous when interpreting such transient skeletal change. In summary, in vivo micro-CT of small laboratory animals can aid in non-clinical safety assessment, particularly for specific mechanistic purposes or to address a particular concern in developmental biology. Copyright © 2014 Elsevier Inc. All rights reserved.

Scattered radiation in fan beam imaging systems

International Nuclear Information System (INIS)

Johns, P.C.; Yaffe, M.

1982-01-01

Scatter-to-primary energy fluence ratios (S/P) have been studied for fan x-ray beams as used in CT scanners and slit projection radiography systems. The dependence of S/P on phantom diameter, distance from phantom to image receptor, and kilovoltage is presented. An empirical equation is given that predicts S/P over a wide range of fan beam imaging configurations. For CT body scans on a 4th-generation machine, S/P is approximately 5%. Scattered radiation can produce a significant cupping artefact in CT images which is similar to that due to beam hardening. When multiple slices are used in scanned slit radiography, they can be arranged such that the increase in S/P is negligible. Calculations of scatter-to-primary ratios for first order scattering showed that for fan beams the contribution of coherent scatter is comparable to or greater than that of incoherent first scatter

Verification of computed tomographic estimates of cochlear implant array position: a micro-CT and histologic analysis.

Science.gov (United States)

Teymouri, Jessica; Hullar, Timothy E; Holden, Timothy A; Chole, Richard A

2011-08-01

To determine the efficacy of clinical computed tomographic (CT) imaging to verify postoperative electrode array placement in cochlear implant (CI) patients. Nine fresh cadaver heads underwent clinical CT scanning, followed by bilateral CI insertion and postoperative clinical CT scanning. Temporal bones were removed, trimmed, and scanned using micro-CT. Specimens were then dehydrated, embedded in either methyl methacrylate or LR White resin, and sectioned with a diamond wafering saw. Histology sections were examined by 3 blinded observers to determine the position of individual electrodes relative to soft tissue structures within the cochlea. Electrodes were judged to be within the scala tympani, scala vestibuli, or in an intermediate position between scalae. The position of the array could be estimated accurately from clinical CT scans in all specimens using micro-CT and histology as a criterion standard. Verification using micro-CT yielded 97% agreement, and histologic analysis revealed 95% agreement with clinical CT results. A composite, 3-dimensional image derived from a patient's preoperative and postoperative CT images using a clinical scanner accurately estimates the position of the electrode array as determined by micro-CT imaging and histologic analyses. Information obtained using the CT method provides valuable insight into numerous variables of interest to patient performance such as surgical technique, array design, and processor programming and troubleshooting.

Cone-beam micro computed tomography dedicated to the breast.

Science.gov (United States)

Sarno, Antonio; Mettivier, Giovanni; Di Lillo, Francesca; Cesarelli, Mario; Bifulco, Paolo; Russo, Paolo

2016-12-01

We developed a scanner for micro computed tomography dedicated to the breast (BµCT) with a high resolution flat-panel detector and a microfocus X-ray tube. We evaluated the system spatial resolution via the 3D modulation transfer function (MTF). In addition to conventional absorption-based X-ray imaging, such a prototype showed capabilities for propagation-based phase-contrast and related edge enhancement effects in 3D imaging. The system limiting spatial resolution is 6.2mm -1 (MTF at 10%) in the vertical direction and 3.8mm -1 in the radial direction, values which compare favorably with the spatial resolution reached by mini focus breast CT scanners of other groups. The BµCT scanner was able to detect both microcalcification clusters and masses in an anthropomorphic breast phantom at a dose comparable to that of two-view mammography. The use of a breast holder is proposed in order to have 1-2min long scan times without breast motion artifacts. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Tumor volume in subcutaneous mouse xenografts measured by microCT is more accurate and reproducible than determined by 18F-FDG-microPET or external caliper

DEFF Research Database (Denmark)

Jensen, Mette Munk; Jørgensen, Jesper Tranekjaer; Binderup, Tina

2008-01-01

BACKGROUND: In animal studies tumor size is used to assess responses to anticancer therapy. Current standard for volumetric measurement of xenografted tumors is by external caliper, a method often affected by error. The aim of the present study was to evaluate if microCT gives more accurate...... (n = 20) was determined in vivo by external caliper, microCT and 18F-FDG-PET and subsequently reference volume was determined ex vivo. Intra-observer reproducibility of the microCT and caliper methods were determined by acquiring 10 repeated volume measurements. Volumes of a group of tumors (n = 10......) were determined independently by two observers to assess inter-observer variation. RESULTS: Tumor volume measured by microCT, PET and caliper all correlated with reference volume. No significant bias of microCT measurements compared with the reference was found, whereas both PET and caliper had...

Microscopic dual-energy CT (microDECT): a flexible tool for multichannel ex vivo 3D imaging of biological specimens.

Science.gov (United States)

Handschuh, S; Beisser, C J; Ruthensteiner, B; Metscher, B D

2017-07-01

material decomposition. We conclude that, in contrast to in vivo DECT examinations, small ex vivo specimens offer some clear advantages regarding technical parameters of the microCT setup and the use of contrast agents. These include a higher flexibility in source peak voltages and x-ray filters, a lower degree of beam hardening due to small sample size, the lack of restriction to nontoxic contrast agents and the lack of a limit in exposure time and radiation dose. We argue that microDECT, because of its flexibility combined with already established contrast agents and the vast number of currently unexploited stains, will in future represent an important technique for various applications in biological research. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Research on applications of rectangular beam in micro laser propulsion

International Nuclear Information System (INIS)

Jiao, L.; Cai, J.; Ma, H.H.; Li, G.X.; Li, L.; Shen, Z.W.; Tang, Z.P.

2014-01-01

Highlights: • Diode laser bar of 808 nm is introduced into the micro laser propulsion field. • Double base propellant (DBP) coating with BOPP substrate was obtained. • The combination of laser power and energy decides the propulsion performance. • The new rectangular beam prefers to produce higher impulse. - Abstract: Micro laser propulsion is a new technology with brilliant future. In order to reduce the thruster mass and volume further, laser bar is introduced into the micro laser propulsion field. A new kind of 220 × 20 μm rectangular beam of 808 nm was obtained by oval lens compressing the light of diode at fast axes and slow axes. The effect of laser power, energy and coating thickness of double base propellant on propulsion performance was studied. Propulsion performance of double base propellant under static and dynamic mode shows some different characters. Compared to round beam, the new beam prefers to produce higher impulse. Ablation efficiency of DBP shows better performance in short laser duration. The combination of power density and energy density decides the laser propulsion performance. The new rectangular beam is appropriate for millisecond micro-laser propulsion

Improved method of in vivo respiratory-gated micro-CT imaging

Energy Technology Data Exchange (ETDEWEB)

Walters, Erin B; Panda, Kunal; Bankson, James A; Brown, Ellana; Cody, Dianna D [Department of Imaging Physics, Unit 56, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 (United States)

2004-09-07

The presence of motion artifacts is a typical problem in thoracic imaging. However, synchronizing the respiratory cycle with computed tomography (CT) image acquisition can reduce these artifacts. We currently employ a method of in vivo respiratory-gated micro-CT imaging for small laboratory animals (mice). This procedure involves the use of a ventilator that controls the respiratory cycle of the animal and provides a digital output signal that is used to trigger data acquisition. After inspection of the default respiratory trigger timing, we hypothesized that image quality could be improved by moving the data-acquisition window to a portion of the cycle with less respiratory motion. For this reason, we developed a simple delay circuit to adjust the timing of the ventilator signal that initiates micro-CT data acquisition. This delay circuit decreases motion artifacts and substantially improves image quality.

Improved method of in vivo respiratory-gated micro-CT imaging

International Nuclear Information System (INIS)

Walters, Erin B; Panda, Kunal; Bankson, James A; Brown, Ellana; Cody, Dianna D

2004-01-01

The presence of motion artifacts is a typical problem in thoracic imaging. However, synchronizing the respiratory cycle with computed tomography (CT) image acquisition can reduce these artifacts. We currently employ a method of in vivo respiratory-gated micro-CT imaging for small laboratory animals (mice). This procedure involves the use of a ventilator that controls the respiratory cycle of the animal and provides a digital output signal that is used to trigger data acquisition. After inspection of the default respiratory trigger timing, we hypothesized that image quality could be improved by moving the data-acquisition window to a portion of the cycle with less respiratory motion. For this reason, we developed a simple delay circuit to adjust the timing of the ventilator signal that initiates micro-CT data acquisition. This delay circuit decreases motion artifacts and substantially improves image quality

Value of micro-CT as an Investigative Tool for Osteochondritis Dissecans. A preliminary study with comparison to histology

International Nuclear Information System (INIS)

Mohr, A.; Bergmann, I.; Muhle, C.; Heller, M.; Heiss, C.; Schrader, C.; Roemer, F.W.; Lynch, J.A.; Genant, H.K.

2003-01-01

Purpose: To evaluate micro computed tomography (micro-CT) for the assessment of osteochondritis dissecans in comparison with histology. Material and Methods: Osteochondritis dissecans lesions of 3 patients were evaluated using micro-CT (0.125 mA, 40 keV, 60 m slice thickness, 60 m isotropic resolution, entire sample) and light microscopy (toluidine blue, 3-5 m slice thickness). The methods were compared regarding preparation time, detectability of tissue types and morphologic features of bone and cartilage. Results: Non-destructive micro-CT imaging of the entire sample was faster than histologic preparation of a single slice for light microscopy. Morphologic features of bone and cartilage could be imaged in a comparable way to histology. It was not possible to image cells or different tissue types of bone and cartilage with micro-CT. Conclusion: Micro-CT is a fast, non-destructive tool that may be a supplement or, if detailed histologic information is not necessary, an alternative to light microscopy for the investigation of osteochondritis dissecans. Osteochondritis dissecans micro-CT histology comparative investigation

SU-F-I-06: Evaluation of Imaging Dose for Modulation Layer Based Dual Energy Cone-Beam CT

Energy Technology Data Exchange (ETDEWEB)

Ju, Eunbin [Department of Medical Science, Ewha Womans University, Seoul (Korea, Republic of); Ahn, SoHyun; Cho, Samju; Keum, Ki Chang [Department of Radiation Oncology, School of Medicine, Yonsei Univeristy, Seoul (Korea, Republic of); Lee, Rena [Department of Radiation Oncology, School of Medicine, Ewha Womans University, Seoul (Korea, Republic of)

2016-06-15

Purpose: Dual energy cone beam CT system is finding a variety of promising applications in diagnostic CT, both in imaging of endogenous materials and exogenous materials across a range of body sites. Dual energy cone beam CT system to suggest in this study acquire image by rotating 360 degree with half of the X-ray window covered using copper modulation layer. In the region that covered by modulation layer absorb the low energy X-ray by modulation layer. Relative high energy X-ray passes through the layer and contributes to image reconstruction. Dose evaluation should be carried out in order to utilize such an imaging acquirement technology for clinical use. Methods: For evaluating imaging dose of modulation layer based dual energy cone beam CT system, Prototype cone beam CT that configured X-ray tube (D054SB, Toshiba, Japan) and detector (PaxScan 2520V, Varian Medical Systems, Palo Alto, CA) is used. A range of 0.5–2.0 mm thickness of modulation layer is implemented in Monte Carlo simulation (MCNPX, ver. 2.6.0, Los Alamos National Laboratory, USA) with half of X-ray window covered. In-house phantom using in this study that has 3 cylindrical phantoms configured water, Teflon air with PMMA covered for verifying the comparability the various material in human body and is implemented in Monte Carlo simulation. The actual dose with 2.0 mm copper covered half of X-ray window is measured using Gafchromic EBT3 film with 5.0 mm bolus for compared with simulative dose. Results: Dose in phantom reduced 33% by copper modulation layer of 2.0 mm. Scattering dose occurred in modulation layer by Compton scattering effect is 0.04% of overall dose. Conclusion: Modulation layer of that based dual energy cone beam CT has not influence on unnecessary scatter dose. This study was supported by the Radiation Safety Research Programs (1305033) through the Nuclear Safety and Security Commission.

An analytical simulation technique for cone-beam CT and pinhole SPECT

International Nuclear Information System (INIS)

Zhang Xuezhu; Qi Yujin

2011-01-01

This study was aimed at developing an efficient simulation technique with an ordinary PC. The work involved derivation of mathematical operators, analytic phantom generations, and effective analytical projectors developing for cone-beam CT and pinhole SPECT imaging. The computer simulations based on the analytical projectors were developed by ray-tracing method for cone-beam CT and voxel-driven method for pinhole SPECT of degrading blurring. The 3D Shepp-Logan, Jaszczak and Defrise phantoms were used for simulation evaluations and image reconstructions. The reconstructed phantom images were of good accuracy with the phantoms. The results showed that the analytical simulation technique is an efficient tool for studying cone-beam CT and pinhole SPECT imaging. (authors)

A characteristic of angiographic cone-beam CT

International Nuclear Information System (INIS)

Takase, Tadashi; Take, Toshio; Nakazawa, Yasuo; Kinouchi, Katsunori

2009-01-01

Angiographic cone-beam CT, called DynaCT by SIEMENS, is a 3D imaging tool reconstructed from projection data by a rotational C-arm with a flat panel detector. It can visualize low-contrast objects such as soft tissue or small vessels as well as high-contrast structures such as enhanced vessels or bone. We need to understand its image characteristics and dose distribution during 200 degree rotation around a patient. In this research, we evaluated fundamental characteristics and dose effectiveness for optimized clinical images. DynaCT, including soft tissue information and isochronal voxel data along the z-axis, could provide enough CT-like image quality for interventional radiology (IVR) use. In addition, evaluation of accumulated dose distribution helped us to predict and avoid the occurrence of radiodermatitis. Thus, DynaCT is useful as a support and navigation tool for IVR. (author)

Quantitative analysis of titanium-induced artifacts and correlated factors during micro-CT scanning.

Science.gov (United States)

Li, Jun Yuan; Pow, Edmond Ho Nang; Zheng, Li Wu; Ma, Li; Kwong, Dora Lai Wan; Cheung, Lim Kwong

2014-04-01

To investigate the impact of cover screw, resin embedment, and implant angulation on artifact of microcomputed tomography (micro-CT) scanning for implant. A total of twelve implants were randomly divided into 4 groups: (i) implant only; (ii) implant with cover screw; (iii) implant with resin embedment; and (iv) implants with cover screw and resin embedment. Implants angulation at 0°, 45°, and 90° were scanned by micro-CT. Images were assessed, and the ratio of artifact volume to total volume (AV/TV) was calculated. A multiple regression analysis in stepwise model was used to determine the significance of different factors. One-way ANOVA was performed to identify which combination of factors could minimize the artifact. In the regression analysis, implant angulation was identified as the best predictor for artifact among the factors (P  0.05). Non-embedded implants with the axis parallel to X-ray source of micro-CT produced minimal artifact. Implant angulation and resin embedment affected the artifact volume of micro-CT scanning for implant, while cover screw did not. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Hard x-ray micro-tomography of a human head post-mortem as a gold standard to compare X-ray modalities

DEFF Research Database (Denmark)

Dalstra, Michel; Schulz, Georg; Dagassan-Berndt, Dorothea

2016-01-01

in a larger study comparing the image quality of various cone beam CT systems currently used in dentistry. The image quality of the micro-CT scans was indeed better than the ones of the clinical imaging modalities, both with regard to noise and streak artifacts due to metal dental implants. Bony features...

MicroCT and microMRI imaging of a prenatal mouse model of increased brain size

Science.gov (United States)

López, Elisabeth K. N.; Stock, Stuart R.; Taketo, Makoto M.; Chenn, Anjen; Ravosa, Matthew J.

2008-08-01

There are surprisingly few experimental models of neural growth and cranial integration. This and the dearth of information regarding fetal brain development detract from a mechanistic understanding of cranial integration and its relevance to the patterning of skull form, specifically the role of encephalization on basicranial flexion. To address this shortcoming, our research uses transgenic mice expressing a stabilized form of β-catenin to isolate the effects of relative brain size on craniofacial development. These mice develop highly enlarged brains due to an increase in neural precursors, and differences between transgenic and wild-type mice are predicted to result solely from variation in brain size. Comparisons of wild-type and transgenic mice at several prenatal ages were performed using microCT (Scanco Medical MicroCT 40) and microMRI (Avance 600 WB MR spectrometer). Statistical analyses show that the larger brain of the transgenic mice is associated with a larger neurocranium and an altered basicranial morphology. However, body size and postcranial ossification do not seem to be affected by the transgene. Comparisons of the rate of postcranial and cranial ossification using microCT also point to an unexpected effect of neural growth on skull development: increased fetal encephalization may result in a compensatory decrease in the level of cranial ossification. Therefore, if other life history factors are held constant, the ontogeny of a metabolically costly structure such as a brain may occur at the expense of other cranial structures. These analyses indicate the benefits of a multifactorial approach to cranial integration using a mouse model.

Cone-beam volume CT mammographic imaging: feasibility study

Science.gov (United States)

Chen, Biao; Ning, Ruola

2001-06-01

X-ray projection mammography, using a film/screen combination or digital techniques, has proven to be the most effective imaging modality for early detection of breast cancer currently available. However, the inherent superimposition of structures makes small carcinoma (a few millimeters in size) difficult to detect in the occultation case or in dense breasts, resulting in a high false positive biopsy rate. The cone-beam x-ray projection based volume imaging using flat panel detectors (FPDs) makes it possible to obtain three-dimensional breast images. This may benefit diagnosis of the structure and pattern of the lesion while eliminating hard compression of the breast. This paper presents a novel cone-beam volume CT mammographic imaging protocol based on the above techniques. Through computer simulation, the key issues of the system and imaging techniques, including the x-ray imaging geometry and corresponding reconstruction algorithms, x-ray characteristics of breast tissues, x-ray setting techniques, the absorbed dose estimation and the quantitative effect of x-ray scattering on image quality, are addressed. The preliminary simulation results support the proposed cone-beam volume CT mammographic imaging modality in respect to feasibility and practicability for mammography. The absorbed dose level is comparable to that of current two-view mammography and would not be a prominent problem for this imaging protocol. Compared to traditional mammography, the proposed imaging protocol with isotropic spatial resolution will potentially provide significantly better low contrast detectability of breast tumors and more accurate location of breast lesions.

Scatter correction, intermediate view estimation and dose characterization in megavoltage cone-beam CT imaging

Science.gov (United States)

Sramek, Benjamin Koerner

neck phantoms. The conclusions of this investigation were: (1) the implementation of intermediate view estimation techniques to megavoltage cone-beam CT produced improvements in image quality, with the largest impact occurring for smaller numbers of initially-acquired projections, (2) the SPECS scatter correction algorithm could be successfully incorporated into projection data acquired using an electronic portal imaging device during megavoltage cone-beam CT image reconstruction, (3) a large range of SPECS parameters were shown to reduce cupping artifacts as well as improve reconstruction accuracy, with application to anthropomorphic phantom geometries improving the percent difference in reconstructed electron density for soft tissue from -13.6% to -2.0%, and for cortical bone from -9.7% to 1.4%, (4) dose measurements in the anthropomorphic phantoms showed consistent agreement between planar measurements using radiochromic film and point measurements using thermoluminescent dosimeters, and (5) a comparison of normalized dose measurements acquired with radiochromic film to those calculated using multiple treatment planning systems, accelerator-detector combinations, patient geometries and accelerator outputs produced a relatively good agreement.

Measurement of erosion of stainless steel by molten lead-free solder using micro-focus x-ray CT system

International Nuclear Information System (INIS)

Nishikawa, Hiroshi; Takemoto, Tadashi; Kang, Songai

2009-01-01

The severe erosion damage, which is caused by a molten lead-free solder, of wave solder equipment made into stainless steel has been encountered in operation. Then, the higher maintenance frequency and reduced life time of wave solder machine component is a serious issue in a manufacturing process. In this study, the evaluation method of erosion of stainless steel by molten lead-free solders was investigated using micro-focus X-ray systems for fluoroscopic and computed tomography (CT). As a result, it was found that the fluoroscopic image could truly reconstruct the cross-shape of the stainless steel sample after immersion test without destruction. In the case of X-ray systems for fluoroscopic and CT used in this study, three-dimensional data can be obtained. Therefore, it was possible to easily check the whole picture of the test sample after immersion test and to decide the maximum erosion depth of test sample. (author)

Evaluation of the adaptation of zirconia-based fixed partial dentures using micro-CT technology

Directory of Open Access Journals (Sweden)

Marcia Borba

2013-09-01

Full Text Available The objective of the study was to measure the marginal and internal fit of zirconia-based all-ceramic three-unit fixed partial dentures (FPDs (Y-TZP - LAVA, 3M-ESPE, using a novel methodology based on micro-computed tomography (micro-CT technology. Stainless steel models of prepared abutments were fabricated to design FPDs. Ten frameworks were produced with 9 mm2 connector cross-sections using a LAVATM CAD-CAM system. All FPDs were veneered with a compatible porcelain. Each FPD was seated on the original model and scanned using micro-CT. Files were processed using NRecon and CTAn software. Adobe Photoshop and Image J software were used to analyze the cross-sectional images. Five measuring points were selected, as follows: MG - marginal gap; CA - chamfer area; AW - axial wall; AOT - axio-occlusal transition area; OA - occlusal area. Results were statistically analyzed by Kruskall-Wallis and Tukey's post hoc test (α= 0.05. There were significant differences for the gap width between the measurement points evaluated. MG showed the smallest median gap width (42 µm. OA had the highest median gap dimension (125 µm, followed by the AOT point (105 µm. CA and AW gap width values were statistically similar, 66 and 65 µm respectively. Thus, it was possible to conclude that different levels of adaptation were observed within the FPD, at the different measuring points. In addition, the micro-CT technology seems to be a reliable tool to evaluate the fit of dental restorations.

Alveolar bone healing in rats: micro-CT, immunohistochemical and molecular analysis

Directory of Open Access Journals (Sweden)

Jaqueline Suemi HASSUMI

2018-06-01

Full Text Available Abstract Alveolar bone healing after upper incisor extraction in rats is a classical model of preclinical studies. The underlying morphometric, cellular and molecular mechanism, however, remains imprecise in a unique study. Objectives The aim of this study was therefore to characterize the alveolar bone healing after upper incisor extraction in rats by micro computed tomographic (Micro-CT, immunohistochemical and real-time polymerase chain reaction (RT-PCR analysis. Material and Methods Thirty animals (Rattus norvegicus, Albinus Wistar were divided into three groups after upper incisors extraction at 7, 14, and 28 days. Micro-CT was evaluated based on the morphometric parameters. Subsequently, the histological analyses and immunostaining of osteoprotegerin (OPG, receptor activator of nuclear kappa B ligand (RANKL and tartrate resistant acid phosphate (TRAP was performed. In addition, RT-PCR analyses of OPG, RANKL, the runt-related transcription factor 2 (RUNX2, osteocalcin (OC, osteopontin (OPN, osterix (OST and receptor activator of nuclear kappa B (RANK were performed to determine the expression of these proteins in the alveolar bone healing. Results Micro-CT: The morphometric parameters of bone volume and trabecular thickness progressively increased over time. Consequently, a gradual decrease in trabecular separation, trabecular space and total bone porosity was observed. Immunohistochemical: There were no differences statistically significant between the positive labeling for OPG, RANKL and TRAP in the different periods. RT-PCR: At 28 days, there was a significant increase in OPG expression, while RANKL expression and the RANKL/OPG ratio both decreased over time. Conclusion Micro-CT showed the newly formed bone had favorable morphometric characteristics of quality and quantity. Beyond the RUNX2, OC, OPN, OST, and RANK proteins expressed in the alveolar bone healing, OPG and RANKL activity showed to be essential for activation of basic

Quantifying lung morphology with respiratory-gated micro-CT in a murine model of emphysema

Science.gov (United States)

Ford, N. L.; Martin, E. L.; Lewis, J. F.; Veldhuizen, R. A. W.; Holdsworth, D. W.; Drangova, M.

2009-04-01

Non-invasive micro-CT imaging techniques have been developed to investigate lung structure in free-breathing rodents. In this study, we investigate the utility of retrospectively respiratory-gated micro-CT imaging in an emphysema model to determine if anatomical changes could be observed in the image-derived quantitative analysis at two respiratory phases. The emphysema model chosen was a well-characterized, genetically altered model (TIMP-3 knockout mice) that exhibits a homogeneous phenotype. Micro-CT scans of the free-breathing, anaesthetized mice were obtained in 50 s and retrospectively respiratory sorted and reconstructed, providing 3D images representing peak inspiration and end expiration with 0.15 mm isotropic voxel spacing. Anatomical measurements included the volume and CT density of the lungs and the volume of the major airways, along with the diameters of the trachea, left bronchus and right bronchus. From these measurements, functional parameters such as functional residual capacity and tidal volume were calculated. Significant differences between the wild-type and TIMP-3 knockout groups were observed for measurements of CT density over the entire lung, indicating increased air content in the lungs of TIMP-3 knockout mice. These results demonstrate retrospective respiratory-gated micro-CT, providing images at multiple respiratory phases that can be analyzed quantitatively to investigate anatomical changes in murine models of emphysema.

Quantifying lung morphology with respiratory-gated micro-CT in a murine model of emphysema

International Nuclear Information System (INIS)

Ford, N L; Martin, E L; Lewis, J F; Veldhuizen, R A W; Holdsworth, D W; Drangova, M

2009-01-01

Non-invasive micro-CT imaging techniques have been developed to investigate lung structure in free-breathing rodents. In this study, we investigate the utility of retrospectively respiratory-gated micro-CT imaging in an emphysema model to determine if anatomical changes could be observed in the image-derived quantitative analysis at two respiratory phases. The emphysema model chosen was a well-characterized, genetically altered model (TIMP-3 knockout mice) that exhibits a homogeneous phenotype. Micro-CT scans of the free-breathing, anaesthetized mice were obtained in 50 s and retrospectively respiratory sorted and reconstructed, providing 3D images representing peak inspiration and end expiration with 0.15 mm isotropic voxel spacing. Anatomical measurements included the volume and CT density of the lungs and the volume of the major airways, along with the diameters of the trachea, left bronchus and right bronchus. From these measurements, functional parameters such as functional residual capacity and tidal volume were calculated. Significant differences between the wild-type and TIMP-3 knockout groups were observed for measurements of CT density over the entire lung, indicating increased air content in the lungs of TIMP-3 knockout mice. These results demonstrate retrospective respiratory-gated micro-CT, providing images at multiple respiratory phases that can be analyzed quantitatively to investigate anatomical changes in murine models of emphysema.

Quantifying lung morphology with respiratory-gated micro-CT in a murine model of emphysema

Energy Technology Data Exchange (ETDEWEB)

Ford, N L [Department of Physics, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Martin, E L; Lewis, J F; Veldhuizen, R A W [Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2 (Canada); Holdsworth, D W; Drangova, M [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada)], E-mail: nlford@ryerson.ca

2009-04-07

Non-invasive micro-CT imaging techniques have been developed to investigate lung structure in free-breathing rodents. In this study, we investigate the utility of retrospectively respiratory-gated micro-CT imaging in an emphysema model to determine if anatomical changes could be observed in the image-derived quantitative analysis at two respiratory phases. The emphysema model chosen was a well-characterized, genetically altered model (TIMP-3 knockout mice) that exhibits a homogeneous phenotype. Micro-CT scans of the free-breathing, anaesthetized mice were obtained in 50 s and retrospectively respiratory sorted and reconstructed, providing 3D images representing peak inspiration and end expiration with 0.15 mm isotropic voxel spacing. Anatomical measurements included the volume and CT density of the lungs and the volume of the major airways, along with the diameters of the trachea, left bronchus and right bronchus. From these measurements, functional parameters such as functional residual capacity and tidal volume were calculated. Significant differences between the wild-type and TIMP-3 knockout groups were observed for measurements of CT density over the entire lung, indicating increased air content in the lungs of TIMP-3 knockout mice. These results demonstrate retrospective respiratory-gated micro-CT, providing images at multiple respiratory phases that can be analyzed quantitatively to investigate anatomical changes in murine models of emphysema.

Three-dimensional focus of attention for iterative cone-beam micro-CT reconstruction

International Nuclear Information System (INIS)

Benson, T M; Gregor, J

2006-01-01

Three-dimensional iterative reconstruction of high-resolution, circular orbit cone-beam x-ray CT data is often considered impractical due to the demand for vast amounts of computer cycles and associated memory. In this paper, we show that the computational burden can be reduced by limiting the reconstruction to a small, well-defined portion of the image volume. We first discuss using the support region defined by the set of voxels covered by all of the projection views. We then present a data-driven preprocessing technique called focus of attention that heuristically separates both image and projection data into object and background before reconstruction, thereby further reducing the reconstruction region of interest. We present experimental results for both methods based on mouse data and a parallelized implementation of the SIRT algorithm. The computational savings associated with the support region are substantial. However, the results for focus of attention are even more impressive in that only about one quarter of the computer cycles and memory are needed compared with reconstruction of the entire image volume. The image quality is not compromised by either method

Mathematical filtering minimizes metallic halation of titanium implants in MicroCT images.

Science.gov (United States)

Ha, Jee; Osher, Stanley J; Nishimura, Ichiro

2013-01-01

Microcomputed tomography (MicroCT) images containing titanium implant suffer from x-rays scattering, artifact and the implant surface is critically affected by metallic halation. To improve the metallic halation artifact, a nonlinear Total Variation denoising algorithm such as Split Bregman algorithm was applied to the digital data set of MicroCT images. This study demonstrated that the use of a mathematical filter could successfully reduce metallic halation, facilitating the osseointegration evaluation at the bone implant interface in the reconstructed images.

Trabecular bone structure parameters from 3D image processing of clinical multi-slice and cone-beam computed tomography data

Energy Technology Data Exchange (ETDEWEB)

Klintstroem, Eva; Smedby, Oerjan [Linkoeping University, Center for Medical Image Science and Visualization (CMIV), Linkoeping (Sweden); UHL County Council of Oestergoetland, Department of Radiology, Linkoeping (Sweden); Linkoeping University, Department of Medical and Health Sciences (IMH)/Radiology, Linkoeping (Sweden); Moreno, Rodrigo [Linkoeping University, Center for Medical Image Science and Visualization (CMIV), Linkoeping (Sweden); Linkoeping University, Department of Medical and Health Sciences (IMH)/Radiology, Linkoeping (Sweden); Brismar, Torkel B. [KUS Huddinge, Department of Clinical Science, Intervention and Technology at Karolinska Institutet and Department of Radiology, Stockholm (Sweden)

2014-02-15

Bone strength depends on both mineral content and bone structure. The aim of this in vitro study was to develop a method of quantitatively assessing trabecular bone structure by applying three-dimensional image processing to data acquired with multi-slice and cone-beam computed tomography using micro-computed tomography as a reference. Fifteen bone samples from the radius were examined. After segmentation, quantitative measures of bone volume, trabecular thickness, trabecular separation, trabecular number, trabecular nodes, and trabecular termini were obtained. The clinical machines overestimated bone volume and trabecular thickness and underestimated trabecular nodes and number, but cone-beam CT to a lesser extent. Parameters obtained from cone beam CT were strongly correlated with μCT, with correlation coefficients between 0.93 and 0.98 for all parameters except trabecular termini. The high correlation between cone-beam CT and micro-CT suggest the possibility of quantifying and monitoring changes of trabecular bone microarchitecture in vivo using cone beam CT. (orig.)

Adaptation Measurement of CAD/CAM Dental Crowns with X-Ray Micro-CT: Metrological Chain Standardization and 3D Gap Size Distribution

Directory of Open Access Journals (Sweden)

L. Tapie

2016-01-01

Full Text Available Computer-Aided Design and Manufacturing systems are increasingly used to produce dental prostheses, but the parts produced suffer from a lack of evaluation, especially concerning the internal gap of the final assembly, that is, the space between the prepared tooth and the prosthesis. X-ray micro-Computed Tomography (micro-CT is a noninvasive imaging technique enabling the internal inspection of the assembly. It has proved to be an efficient tool for measuring the gap. In this study, a critical review of the protocols using micro-CT to quantify the gap is proposed as an introduction to a new protocol aimed at minimizing errors and enabling comparison between CAD/CAM systems. To compare different systems, a standardized protocol is proposed including two reference geometries. Micro-CT is used to acquire the reference geometries. A new 3D method is then proposed and a new indicator is defined (Gap Size Distribution (GSD. In addition, the usual 2D measurements are described and discussed. The 3D gap measurement method proposed can be used in clinical case geometries and has the considerable advantage of minimizing the data processing steps before performing the measurements.

Development of a bent Laue beam-expanding double-crystal monochromator for biomedical X-ray imaging

International Nuclear Information System (INIS)

Martinson, Mercedes; Samadi, Nazanin; Belev, George; Bassey, Bassey; Lewis, Rob; Aulakh, Gurpreet; Chapman, Dean

2014-01-01

A bent Laue beam-expanding double-crystal monochromator was developed and tested at the Biomedical Imaging and Therapy beamline at the Canadian Light Source. The expander will reduce scanning time for micro-computed tomography and allow dynamic imaging that has not previously been possible at this beamline. The Biomedical Imaging and Therapy (BMIT) beamline at the Canadian Light Source has produced some excellent biological imaging data. However, the disadvantage of a small vertical beam limits its usability in some applications. Micro-computed tomography (micro-CT) imaging requires multiple scans to produce a full projection, and certain dynamic imaging experiments are not possible. A larger vertical beam is desirable. It was cost-prohibitive to build a longer beamline that would have produced a large vertical beam. Instead, it was proposed to develop a beam expander that would create a beam appearing to originate at a source much farther away. This was accomplished using a bent Laue double-crystal monochromator in a non-dispersive divergent geometry. The design and implementation of this beam expander is presented along with results from the micro-CT and dynamic imaging tests conducted with this beam. Flux (photons per unit area per unit time) has been measured and found to be comparable with the existing flat Bragg double-crystal monochromator in use at BMIT. This increase in overall photon count is due to the enhanced bandwidth of the bent Laue configuration. Whilst the expanded beam quality is suitable for dynamic imaging and micro-CT, further work is required to improve its phase and coherence properties

A comparative study for spatial resolution and subjective image characteristics of a multi-slice CT and a cone-beam CT for dental use

International Nuclear Information System (INIS)

Watanabe, Hiroshi; Honda, Eiichi; Tetsumura, Akemi; Kurabayashi, Tohru

2011-01-01

Purpose: Multi-slice CT (MSCT) and cone-beam CT (CBCT) are widely used in dental practice. This study compared the spatial resolution of these CT systems to elucidate which CT modalities should be selected for various clinical cases. Materials and methods: As MSCT and CBCT apparatuses, Somatom Sensation 64 and 3D Accuitomo instruments, respectively, were used. As an objective evaluation of spatial resolution of these CT systems, modulation transfer function (MTF) analysis was performed employing an over-sampling method. The results of MTF analysis were confirmed with a line-pair test using CATPHAN. As a subjective evaluation, a microstructure visualization ability study was performed using a Jcl:SD rat and a head CT phantom. Results: MTF analysis showed that for the in-plane direction, the z-axis ultrahigh resolution mode (zUHR) of the Sensation 64 and 3D Accuitomo instruments had higher spatial resolutions than the conventional mode (64x) of the Sensation 64, but for the longitudinal direction, the 3D Accuitomo had clearly higher spatial resolution than either mode of the Sensation 64. A line-pair test study and microstructure visualization ability studies confirmed the results for MTF analysis. However, images of the rat and the CT phantom revealed that the 3D Accuitomo demonstrated the failure to visualize the soft tissues along with aliasing and beam-hardening artifacts, which were not observed in the Sensation 64. Conclusions: This study successfully applied spatial resolution analysis using MSCT and CBCT systems in a comparative manner. These findings could help in deciding which CT modality should be selected for various clinical cases.

Region-of-interest reconstruction for a cone-beam dental CT with a circular trajectory

International Nuclear Information System (INIS)

Hu, Zhanli; Zou, Jing; Gui, Jianbao; Zheng, Hairong; Xia, Dan

2013-01-01

Dental CT is the most appropriate and accurate device for preoperative evaluation of dental implantation. It can demonstrate the quantity of bone in three dimensions (3D), the location of important adjacent anatomic structures and the quality of available bone with minimal geometric distortion. Nevertheless, with the rapid increase of dental CT examinations, we are facing the problem of dose reduction without loss of image quality. In this work, backprojection-filtration (BPF) and Feldkamp–Davis–Kress (FDK) algorithm was applied to reconstruct the 3D full image and region-of-interest (ROI) image from complete and truncated circular cone-beam data respectively by computer-simulation. In addition, the BPF algorithm was evaluated based on the 3D ROI-image reconstruction from real data, which was acquired from our developed circular cone-beam prototype dental CT system. The results demonstrated that the ROI-image quality reconstructed from truncated data using the BPF algorithm was comparable to that reconstructed from complete data. The FDK algorithm, however, created artifacts while reconstructing ROI-image. Thus it can be seen, for circular cone-beam dental CT, reducing scanning angular range of the BPF algorithm used for ROI-image reconstruction are helpful for reducing the radiation dose and scanning time. Finally, an analytical method was developed for estimation of the ROI projection area on the detector before CT scanning, which would help doctors to roughly estimate the total radiation dose before the CT examination. -- Highlights: ► BPF algorithm was applied by using dental CT for the first time. ► A method was developed for estimation of projection region before CT scanning. ► Roughly predict the total radiation dose before CT scans. ► Potential reduce imaging radiation dose, scatter, and scanning time

Resolution Improvement and Pattern Generator Development for the Maskless Micro-Ion-Beam Reduction Lithography System

International Nuclear Information System (INIS)

Jiang, Ximan

2006-01-01

The shrinking of IC devices has followed the Moore's Law for over three decades, which states that the density of transistors on integrated circuits will double about every two years. This great achievement is obtained via continuous advance in lithography technology. With the adoption of complicated resolution enhancement technologies, such as the phase shifting mask (PSM), the optical proximity correction (OPC), optical lithography with wavelength of 193 nm has enabled 45 nm printing by immersion method. However, this achievement comes together with the skyrocketing cost of masks, which makes the production of low volume application-specific IC (ASIC) impractical. In order to provide an economical lithography approach for low to medium volume advanced IC fabrication, a maskless ion beam lithography method, called Maskless Micro-ion-beam Reduction Lithography (MMRL), has been developed in the Lawrence Berkeley National Laboratory. The development of the prototype MMRL system has been described by Dr. Vinh Van Ngo in his Ph.D. thesis. But the resolution realized on the prototype MMRL system was far from the design expectation. In order to improve the resolution of the MMRL system, the ion optical system has been investigated. By integrating a field-free limiting aperture into the optical column, reducing the electromagnetic interference and cleaning the RF plasma, the resolution has been improved to around 50 nm. Computational analysis indicates that the MMRL system can be operated with an exposure field size of 0.25 mm and a beam half angle of 1.0 mrad on the wafer plane. Ion-ion interactions have been studied with a two-particle physics model. The results are in excellent agreement with those published by the other research groups. The charge-interaction analysis of MMRL shows that the ion-ion interactions must be reduced in order to obtain a throughput higher than 10 wafers per hour on 300-mm wafers. In addition, two different maskless lithography strategies

Performance evaluation of a compact PET/SPECT/CT tri-modality system for small animal imaging applications

International Nuclear Information System (INIS)

Wei, Qingyang; Wang, Shi; Ma, Tianyu; Wu, Jing; Liu, Hui; Xu, Tianpeng; Xia, Yan; Fan, Peng; Lyu, Zhenlei; Liu, Yaqiang

2015-01-01

PET, SPECT and CT imaging techniques are widely used in preclinical small animal imaging applications. In this paper, we present a compact small animal PET/SPECT/CT tri-modality system. A dual-functional, shared detector design is implemented which enables PET and SPECT imaging with a same LYSO ring detector. A multi-pinhole collimator is mounted on the system and inserted into the detector ring in SPECT imaging mode. A cone-beam CT consisting of a micro focus X-ray tube and a CMOS detector is implemented. The detailed design and the performance evaluations are reported in this paper. In PET imaging mode, the measured NEMA based spatial resolution is 2.12 mm (FWHM), and the sensitivity at the central field of view (CFOV) is 3.2%. The FOV size is 50 mm (∅)×100 mm (L). The SPECT has a spatial resolution of 1.32 mm (FWHM) and an average sensitivity of 0.031% at the center axial, and a 30 mm (∅)×90 mm (L) FOV. The CT spatial resolution is 8.32 lp/mm @10%MTF, and the contrast discrimination function value is 2.06% with 1.5 mm size cubic box object. In conclusion, a compact, tri-modality PET/SPECT/CT system was successfully built with low cost and high performance

Micro-CT scan reveals an unexpected high-volume and interconnected pore network in a Cretaceous Sanagasta dinosaur eggshell.

Science.gov (United States)

Hechenleitner, E Martín; Grellet-Tinner, Gerald; Foley, Matthew; Fiorelli, Lucas E; Thompson, Michael B

2016-03-01

The Cretaceous Sanagasta neosauropod nesting site (La Rioja, Argentina) was the first confirmed instance of extinct dinosaurs using geothermal-generated heat to incubate their eggs. The nesting strategy and hydrothermal activities at this site led to the conclusion that the surprisingly 7 mm thick-shelled eggs were adapted to harsh hydrothermal microenvironments. We used micro-CT scans in this study to obtain the first three-dimensional microcharacterization of these eggshells. Micro-CT-based analyses provide a robust assessment of gas conductance in fossil dinosaur eggshells with complex pore canal systems, allowing calculation, for the first time, of the shell conductance through its thickness. This novel approach suggests that the shell conductance could have risen during incubation to seven times more than previously estimated as the eggshell erodes. In addition, micro-CT observations reveal that the constant widening and branching of pore canals form a complex funnel-like pore canal system. Furthermore, the high density of pore canals and the presence of a lateral canal network in the shell reduce the risks of pore obstruction during the extended incubation of these eggs in a relatively highly humid and muddy nesting environment. © 2016 The Author(s).

Partial volume and aliasing artefacts in helical cone-beam CT

International Nuclear Information System (INIS)

Zou Yu; Sidky, Emil Y; Pan, Xiaochuan

2004-01-01

A generalization of the quasi-exact algorithms of Kudo et al (2000 IEEE Trans. Med. Imaging 19 902-21) is developed that allows for data acquisition in a 'practical' frame for clinical diagnostic helical, cone-beam computed tomography (CT). The algorithm is investigated using data that model nonlinear partial volume averaging. This investigation leads to an understanding of aliasing artefacts in helical, cone-beam CT image reconstruction. An ad hoc scheme is proposed to mitigate artefacts due to the nonlinear partial volume and aliasing artefacts

MicroCT vs. Hg porosimetry: microporosity in commercial stones

Science.gov (United States)

Fusi, N.; Martinez-Martinez, J.; Barberini, V.; Galimberti, L.

2009-04-01

have been cut and scanned by means of a X ray microCT system before and after mercury saturation with Hg porosimeter. The microCT system used is a BIR Actis 130/150 with nominal resolution of 5 micron; for our samples resolution is of 25 microns. Generator and detector are fixed, while the sample rotates; the scanning plane is horizontal. Samples reduce the X rays energy passing through, as a function of its density and atomic number. X rays are then collected on a detector, which converts them into light radiations; a digital camera collects light radiations in raw data and send them to the computer, where they are processed as black/white images. The Hg porosimeter used is a Pascal 140/240 Thermo Fisher. Samples were first degassed and then intruded by Hg. Apparent density, bulk density, porosity and open pore size distribution (pore diameter between 3.7 and 58000 nm) of each sample have been computed using the PASCAL (Pressurization with Automatic Speed-up by Continuous Adjustametnt Logic) method and the Washburn equation; this equation assumes: cylindrical pores, a contact angle between mercury and sample of 140°, a surface tension of mercury vacuum of 0,480 N/m and mercury density equal to 13.5 g/cm³. MicroCT images and porosity data from Hg porosimeter have been compared by several authors both for rocks (Klobes et alii, 1997) and for artificial materials with medical applications (Lin-Gibson et alii, 2007) In samples with no density/composition differences microCT images are homogeneous and gives no information on the internal structure of the sample. This is the case of massive samples (such as BA, BT, GM and TB) and of samples without any significant density differences between clasts and matrix (A and BS) or rock and veins (RC). MicroCT images of the same sample after mercury saturation offer a detailed map of microporosity of the rock, due to the high density contrast between mercury (13.6 g/cm3) and the rock (2.71 g/cm3 for calcite and 2.86 g/cm3 for

THz computed tomography system with zero-order Bessel beam

Science.gov (United States)

Niu, Liting; Wu, Qiao; Wang, Kejia; Liu, Jinsong; Yang, Zhengang

2018-01-01

Terahertz (THz) waves can penetrate many optically opaque dielectric materials such as plastics, ceramics and colorants. It is effective to reveal the internal structures of these materials. We have built a THz Computed Tomography (CT) system with 0.3 THz zero-order Bessel beam to improve the depth of focus of this imaging system for the non-diffraction property of Bessel beam. The THz CT system has been used to detect a paper cup with a metal rod inside. Finally, the acquired projection data have been processed by the filtered back-projection algorithm and the reconstructed image of the sample has been obtained.

Evaluation of the adaptation of zirconia-based fixed partial dentures using micro-CT technology

Energy Technology Data Exchange (ETDEWEB)

Borba, Marcia; Bona, Alvaro Della, E-mail: marcia_borb@hotmail.com [Universidade de Passo Fundo (UPF), RS (Brazil). Fac. de Odontologia; Miranda Junior, Walter Gomes; Cesar, Paulo Francisco [Universidade de Sao Paulo (USP), SP (Brazil). Fac. de Odontologia. Dept. de Biomateriais e Bioquimica Oral; Griggs, Jason Allan [Department of Biomedical Materials Science, Dental School, University of Mississippi Medical Center - UMMC, Jackson, MS (United States)

2013-09-15

The objective of the study was to measure the marginal and internal fit of zirconia-based all-ceramic three-unit fixed partial dentures (FPDs) (Y-TZP - LAVA, 3M-ESPE), using a novel methodology based on micro-computed tomography (micro-CT) technology. Stainless steel models of prepared abutments were fabricated to design FPDs. Ten frameworks were produced with 9 mm² connector cross-sections using a LAVA® CAD-CAM system. All FPDs were veneered with a compatible porcelain. Each FPD was seated on the original model and scanned using micro-CT. Files were processed using NRecon and CTAn software. Adobe Photoshop and Image J software were used to analyze the cross sectional images. Five measuring points were selected, as follows: MG- marginal gap; CA - chamfer area; AW - axial wall; AOT - axio-occlusal transition area; OA - occlusal area. Results were statistically analyzed by Kruskall-Wallis and Tukey's post hoc test (α = 0.05). There were significant differences for the gap width between the measurement points evaluated. MG showed the smallest median gap width (42 μm). OA had the highest median gap dimension (125 μm), followed by the AOT point (105 μm). CA and AW gap width values were statistically similar, 66 and 65 μm respectively. Thus, it was possible to conclude that different levels of adaptation were observed within the FPD, at the different measuring points. In addition, the micro-CT technology seems to be a reliable tool to evaluate the fit of dental restorations. (author)

Evaluation of the adaptation of zirconia-based fixed partial dentures using micro-CT technology

International Nuclear Information System (INIS)

Borba, Marcia; Bona, Alvaro Della

2013-01-01

The objective of the study was to measure the marginal and internal fit of zirconia-based all-ceramic three-unit fixed partial dentures (FPDs) (Y-TZP - LAVA, 3M-ESPE), using a novel methodology based on micro-computed tomography (micro-CT) technology. Stainless steel models of prepared abutments were fabricated to design FPDs. Ten frameworks were produced with 9 mm² connector cross-sections using a LAVA® CAD-CAM system. All FPDs were veneered with a compatible porcelain. Each FPD was seated on the original model and scanned using micro-CT. Files were processed using NRecon and CTAn software. Adobe Photoshop and Image J software were used to analyze the cross sectional images. Five measuring points were selected, as follows: MG- marginal gap; CA - chamfer area; AW - axial wall; AOT - axio-occlusal transition area; OA - occlusal area. Results were statistically analyzed by Kruskall-Wallis and Tukey's post hoc test (α = 0.05). There were significant differences for the gap width between the measurement points evaluated. MG showed the smallest median gap width (42 μm). OA had the highest median gap dimension (125 μm), followed by the AOT point (105 μm). CA and AW gap width values were statistically similar, 66 and 65 μm respectively. Thus, it was possible to conclude that different levels of adaptation were observed within the FPD, at the different measuring points. In addition, the micro-CT technology seems to be a reliable tool to evaluate the fit of dental restorations. (author)

Investigation of bulk electron densities for dose calculations on cone-beam CT images

International Nuclear Information System (INIS)

Lambert, J.; Parker, J.; Gupta, S.; Hatton, J.; Tang, C.; Capp, A.; Denham, J.W.; Wright, P.

2010-01-01

Full text: If cone-beam CT images are to be used for dose calculations, then the images must be able to provide accurate electron density information. Twelve patients underwent twice weekly cone-beam CT scans in addition to the planning CT scan. A standardised 5-field treatment plan was applied to 169 of the CBCT images. Doses were calculated using the original electron density values in the CBCT and with bulk electron densities applied. Bone was assigned a density of 288 HU, and all other tissue was assigned to be water equivalent (0 HU). The doses were compared to the dose calculated on the original planning CT image. Using the original HU values in the cone-beam images, the average dose del i vered by the plans from all 12 patients was I. I % lower than the intended 200 cOy delivered on the original CT plans (standard devia tion 0.7%, maximum difference -2.93%). When bulk electron densities were applied to the cone-beam images, the average dose was 0.3% lower than the original CT plans (standard deviation 0.8%, maximum difference -2.22%). Compared to using the original HU values, applying bulk electron densities to the CBCT images improved the dose calculations by almost I %. Some variation due to natural changes in anatomy should be expected. The application of bulk elec tron densities to cone beam CT images has the potential to improve the accuracy of dose calculations due to inaccurate H U values. Acknowledgements This work was partially funded by Cancer Council NSW Grant Number RG 07-06.

Exploring miniature insect brains using micro-CT scanning techniques

Science.gov (United States)

Smith, Dylan B.; Bernhardt, Galina; Raine, Nigel E.; Abel, Richard L.; Sykes, Dan; Ahmed, Farah; Pedroso, Inti; Gill, Richard J.

2016-01-01

The capacity to explore soft tissue structures in detail is important in understanding animal physiology and how this determines features such as movement, behaviour and the impact of trauma on regular function. Here we use advances in micro-computed tomography (micro-CT) technology to explore the brain of an important insect pollinator and model organism, the bumblebee (Bombus terrestris). Here we present a method for accurate imaging and exploration of insect brains that keeps brain tissue free from trauma and in its natural stereo-geometry, and showcase our 3D reconstructions and analyses of 19 individual brains at high resolution. Development of this protocol allows relatively rapid and cost effective brain reconstructions, making it an accessible methodology to the wider scientific community. The protocol describes the necessary steps for sample preparation, tissue staining, micro-CT scanning and 3D reconstruction, followed by a method for image analysis using the freeware SPIERS. These image analysis methods describe how to virtually extract key composite structures from the insect brain, and we demonstrate the application and precision of this method by calculating structural volumes and investigating the allometric relationships between bumblebee brain structures. PMID:26908205

Micro-CT image reconstruction based on alternating direction augmented Lagrangian method and total variation.

Science.gov (United States)

Gopi, Varun P; Palanisamy, P; Wahid, Khan A; Babyn, Paul; Cooper, David

2013-01-01

Micro-computed tomography (micro-CT) plays an important role in pre-clinical imaging. The radiation from micro-CT can result in excess radiation exposure to the specimen under test, hence the reduction of radiation from micro-CT is essential. The proposed research focused on analyzing and testing an alternating direction augmented Lagrangian (ADAL) algorithm to recover images from random projections using total variation (TV) regularization. The use of TV regularization in compressed sensing problems makes the recovered image quality sharper by preserving the edges or boundaries more accurately. In this work TV regularization problem is addressed by ADAL which is a variant of the classic augmented Lagrangian method for structured optimization. The per-iteration computational complexity of the algorithm is two fast Fourier transforms, two matrix vector multiplications and a linear time shrinkage operation. Comparison of experimental results indicate that the proposed algorithm is stable, efficient and competitive with the existing algorithms for solving TV regularization problems. Copyright © 2013 Elsevier Ltd. All rights reserved.

HOT SPOT RELIEF WITH EMBEDDED BEAM FOR CDMA SYSTEMS IN HAPS

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

This paper proposes a novel micro/macro beam coverage scheme used in High Altitude Platform System (HAPS) Code Division Multiple Access (CDMA) systems. A relief of traffic burden in hot spot areas is achieved by embedding micro-beams into the macro-beams at the hot spot locations, together with appropriate power ratio control and user ratio control. The simulation results show that the hot spot problem can be relieved efficiently with the presented configuration, and a higher and more stable system capacity is expectable despite the variation of user distribution.

X-ray micro-CT and neutron CT as complementary imaging tools for non-destructive 3D imaging of rare silicified fossil plants

Science.gov (United States)

Karch, J.; Dudák, J.; Žemlička, J.; Vavřík, D.; Kumpová, I.; Kvaček, J.; Heřmanová, Z.; Šoltés, J.; Viererbl, L.; Morgano, M.; Kaestner, A.; Trtík, P.

2017-12-01

Computed tomography provides 3D information of inner structures of investigated objects. The obtained information is, however, strongly dependent on the used radiation type. It is known that as X-rays interact with electron cloud and neutrons with atomic nucleus, the obtained data often provide different contrast of sample structures. In this work we present a set of comparative radiographic and CT measurements of rare fossil plant samples using X-rays and thermal neutrons. The X-ray measurements were performed using large area photon counting detectors Timepix at IEAP CTU in Prague and Perkin Elmer flat-panel detector at Center of Excellence Telč. The neutron CT measurement was carried out at Paul Scherrer Institute using BOA beam-line. Furthermore, neutron radiography of fossil samples, provided by National Museum, were performed using a large-area Timepix detector with a neutron-sensitive converting 6LiF layer at Research Centre Rez, Czech Republic. The obtained results show different capabilities of both imaging approaches. While X-ray micro-CT provides very high resolution and enables visualization of fine cracks or small cavities in the samples neutron imaging provides high contrast of morphological structures of fossil plant samples, where X-ray imaging provides insufficient contrast.

Delayed contrast enhancement imaging of a murine model for ischemia reperfusion with carbon nanotube micro-CT.

Directory of Open Access Journals (Sweden)

Laurel M Burk

Full Text Available We aim to demonstrate the application of free-breathing prospectively gated carbon nanotube (CNT micro-CT by evaluating a myocardial infarction model with a delayed contrast enhancement technique. Evaluation of murine cardiac models using micro-CT imaging has historically been limited by extreme imaging requirements. Newly-developed CNT-based x-ray sources offer precise temporal resolution, allowing elimination of physiological motion through prospective gating. Using free-breathing, cardiac-gated CNT micro-CT, a myocardial infarction model can be studied non-invasively and with high resolution. Myocardial infarction was induced in eight male C57BL/6 mice aged 8-12 weeks. The ischemia reperfusion model was achieved by surgically occluding the LAD artery for 30 minutes followed by 24 hours of reperfusion. Tail vein catheters were placed for contrast administration. Iohexol 300 mgI/mL was administered followed by images obtained in diastole. Iodinated lipid blood pool contrast agent was then administered, followed with images at systole and diastole. Respiratory and cardiac signals were monitored externally and used to gate the scans of free-breathing subjects. Seven control animals were scanned using the same imaging protocol. After imaging, the heart was harvested, cut into 1mm slices and stained with TTC. Post-processing analysis was performed using ITK-Snap and MATLAB. All animals demonstrated obvious delayed contrast enhancement in the left ventricular wall following the Iohexol injection. The blood pool contrast agent revealed significant changes in cardiac function quantified by 3-D volume ejection fractions. All subjects demonstrated areas of myocardial infarct in the LAD distribution on both TTC staining and micro-CT imaging. The CNT micro-CT system aids straightforward, free-breathing, prospectively-gated 3-D murine cardiac imaging. Delayed contrast enhancement allows identification of infarcted myocardium after a myocardial ischemic

MicroCT Analysis of Micro-Nano Titanium Implant Surface on the Osseointegration.

Science.gov (United States)

Ban, Jaesam; Kang, Seongsoo; Kim, Jihyun; Lee, Kwangmin; Hyunpil, Lim; Vang, Mongsook; Yang, Hongso; Oh, Gyejeong; Kim, Hyunseung; Hwang, Gabwoon; Jung, Yongho; Lee, Kyungku; Park, Sangwon; Yunl, Kwidug

2015-01-01

This study was to investigate the effects of micro-nano titanium implant surface on the osseointegration. A total of 36 screw-shaped implants were used. The implant surfaces were classified into 3 groups (n = 12): machined surface (M group), nanosurface which is nanotube formation on the machined surface (MA group) and nano-micro surface which is nanotube formation on the RBM surface (RA group). Anodic oxidation was performed at a 20 V for 10 min with 1 M H3PO4 and 1.5 wt% HF solutions. The implants were installed on the humerus on 6 beagles. After 4 and 12 weeks, the morphometric analysis with micro CT (skyscan 1172, SKYSCAN, Antwerpen, Belgium) was done. The data were statistically analyzed with two-way ANOVA. Bone mineral density and bone volume were significantly increased depending on time. RA group showed the highest bone mineral density and bone volume at 4 weeks and 12 weeks significantly. It indicated that nano-micro titanium implant surface showed faster and more mature osseointegration.

MEMS Tunneling Micro Thermometer Based onTip Deflection of Bimetallic Cantilever Beam

Directory of Open Access Journals (Sweden)

Samrand K. Nezhadian

2007-10-01

Full Text Available Micro-electro-mechanical (MEM technology promises to significantly reduce the size, weight and cost of a variety of sensor systems. In this article has been described a highly sensitive novel type of thermometer based on deflection of a “bimetallic” microbeam. The proposed thermometer converts the thermal changes of a cantilevered bimetallic beam of submillimeter size into an electrical signal through tunneling-current modulation. The governing thermo-mechanical equation of a bimetallic cantilever beam has been derived and solved analytically. The obtained results show that the proposed tunneling micro thermometer is very sensitive to temperature changes due to exponential increasing of tunneling current but because of small gap between metallic electrodes, measurable range of temperature changes is small.

System matrix computation vs storage on GPU: A comparative study in cone beam CT.

Science.gov (United States)

Matenine, Dmitri; Côté, Geoffroi; Mascolo-Fortin, Julia; Goussard, Yves; Després, Philippe

2018-02-01

Iterative reconstruction algorithms in computed tomography (CT) require a fast method for computing the intersection distances between the trajectories of photons and the object, also called ray tracing or system matrix computation. This work focused on the thin-ray model is aimed at comparing different system matrix handling strategies using graphical processing units (GPUs). In this work, the system matrix is modeled by thin rays intersecting a regular grid of box-shaped voxels, known to be an accurate representation of the forward projection operator in CT. However, an uncompressed system matrix exceeds the random access memory (RAM) capacities of typical computers by one order of magnitude or more. Considering the RAM limitations of GPU hardware, several system matrix handling methods were compared: full storage of a compressed system matrix, on-the-fly computation of its coefficients, and partial storage of the system matrix with partial on-the-fly computation. These methods were tested on geometries mimicking a cone beam CT (CBCT) acquisition of a human head. Execution times of three routines of interest were compared: forward projection, backprojection, and ordered-subsets convex (OSC) iteration. A fully stored system matrix yielded the shortest backprojection and OSC iteration times, with a 1.52× acceleration for OSC when compared to the on-the-fly approach. Nevertheless, the maximum problem size was bound by the available GPU RAM and geometrical symmetries. On-the-fly coefficient computation did not require symmetries and was shown to be the fastest for forward projection. It also offered reasonable execution times of about 176.4 ms per view per OSC iteration for a detector of 512 × 448 pixels and a volume of 384 3 voxels, using commodity GPU hardware. Partial system matrix storage has shown a performance similar to the on-the-fly approach, while still relying on symmetries. Partial system matrix storage was shown to yield the lowest relative

An optimization-based method for geometrical calibration in cone-beam CT without dedicated phantoms

International Nuclear Information System (INIS)

Panetta, D; Belcari, N; Guerra, A Del; Moehrs, S

2008-01-01

In this paper we present a new method for the determination of geometrical misalignments in cone-beam CT scanners, from the analysis of the projection data of a generic object. No a priori knowledge of the object shape and positioning is required. We show that a cost function, which depends on the misalignment parameters, can be defined using the projection data and that such a cost function has a local minimum in correspondence to the actual parameters of the system. Hence, the calibration of the scanner can be carried out by minimizing the cost function using standard optimization techniques. The method is developed for a particular class of 3D object functions, for which the redundancy of the fan beam sinogram in the transaxial midplane can be extended to cone-beam projection data, even at wide cone angles. The method has an approximated validity for objects which do not belong to that class; in that case, a suitable subset of the projection data can be selected in order to compute the cost function. We show by numerical simulations that our method is capable to determine with high accuracy the most critical misalignment parameters of the scanner, i.e., the transversal shift and the skew of the detector. Additionally, the detector slant can be determined. Other parameters such as the detector tilt, the longitudinal shift and the error in the source-detector distance cannot be determined with our method, as the proposed cost function has a very weak dependence on them. However, due to the negligible influence of these latter parameters in the reconstructed image quality, they can be kept fixed at estimated values in both calibration and reconstruction processes without compromising the final result. A trade-off between computational cost and calibration accuracy must be considered when choosing the data subset used for the computation of the cost function. Results on real data of a mouse femur as obtained with a small animal micro-CT are shown as well, proving

Experimental validation of a rapid Monte Carlo based micro-CT simulator

International Nuclear Information System (INIS)

Colijn, A P; Zbijewski, W; Sasov, A; Beekman, F J

2004-01-01

We describe a newly developed, accelerated Monte Carlo simulator of a small animal micro-CT scanner. Transmission measurements using aluminium slabs are employed to estimate the spectrum of the x-ray source. The simulator incorporating this spectrum is validated with micro-CT scans of physical water phantoms of various diameters, some containing stainless steel and Teflon rods. Good agreement is found between simulated and real data: normalized error of simulated projections, as compared to the real ones, is typically smaller than 0.05. Also the reconstructions obtained from simulated and real data are found to be similar. Thereafter, effects of scatter are studied using a voxelized software phantom representing a rat body. It is shown that the scatter fraction can reach tens of per cents in specific areas of the body and therefore scatter can significantly affect quantitative accuracy in small animal CT imaging

The generation of high-power charge particle micro beams and its interaction with condensed matter

International Nuclear Information System (INIS)

Vogel, N.; Skvortsov, V.A.

1996-01-01

As has been observed experimentally, the action of a picosecond laser beam on an Al-target in air gives rise to the generation and acceleration of high-power micro electron and ion beams. An original theoretical model for describing the generation and particle acceleration of such micro beams as a result of the micro channeling effect is presented. It was found that extreme states of matter, with compression in the Gbar pressure range, can be produced by such micro beams. (author). 3 figs., 12 refs

SU-E-T-143: Effect of X-Ray and Cone Beam CT Reconstruction Parameters On Estimation of Bone Volume of Mice Used in Aging Research

Energy Technology Data Exchange (ETDEWEB)

Russ, M; Pang, M; Troen, B; Rudin, S; Ionita, C [University at Buffalo, Buffalo, NY (United States)

2014-06-01

Purpose: To investigate the variations in bone volume calculations in mice involved in aging research when changing cone beam micro-CT x-ray and reconstruction parameters. Methods: Mouse spines were placed on an indexed turn table that rotated 0.5° per projection and imaged by a self-built micro CT machine containing a CCD-based high-resolution x-ray detector. After the full 360° rotation data set of object images was obtained, a standard filtered back-projection cone beam reconstruction was performed. Four different kVp's between 40–70 kVp in 10kVp increments were selected. For each kVp two mAs settings were used. Each acquisition was reconstructed using two voxel sizes (12 and 25μm) and two step angles, 0.5° and 1°, respectively. A LabView program was written to determine the total bone volume contained in the mouse's total spine volume (bone plus gaps) as a measure of spine health. First, the user selected the desired 512×512 reconstruction to view the whole spine volume which was then used to select a gray-level threshold that allowed for viewing of the bone structure, then another threshold to include gaps. The program returned bone volume, bone × gap volume, and their ratio, BVF. Results: The calculated bone volume fractions were compared as a function of tube potential. Cases with 25μm slice thickness showed trials with lower kVp's had greater image contrast, which resulted in higher calculated bone volume fractions. Cases with 12μm reconstructed slice thickness were significantly noisier, and showed no clear maximum BVF. Conclusion: Using the projection images and reconstructions acquired from the micro CT, it can be shown that the micro-CT x-ray and reconstruction parameters significantly affect the total bone volume calculations. When comparing mice cohorts treated with different therapies researchers need to be aware of such details and use volumes which were acquired and processed in identical conditions.

A One-Step Cone-Beam CT-Enabled Planning-to-Treatment Model for Palliative Radiotherapy-From Development to Implementation

Energy Technology Data Exchange (ETDEWEB)

Wong, Rebecca K.S., E-mail: rebecca.wong@rmp.uhn.on.ca [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Letourneau, Daniel; Varma, Anita [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Bissonnette, Jean Pierre; Fitzpatrick, David; Grabarz, Daniel; Elder, Christine [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Martin, Melanie; Bezjak, Andrea [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Panzarella, Tony [Department of Biostatistics, Princess Margaret Hospital, Toronto, Ontario (Canada); Gospodarowicz, Mary [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Jaffray, David A. [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario (Canada)

2012-11-01

Purpose: To develop a cone-beam computed tomography (CT)-enabled one-step simulation-to-treatment process for the treatment of bone metastases. Methods and Materials: A three-phase prospective study was conducted. Patients requiring palliative radiotherapy to the spine, mediastinum, or abdomen/pelvis suitable for treatment with simple beam geometry ({<=}2 beams) were accrued. Phase A established the accuracy of cone-beam CT images for the purpose of gross tumor target volume (GTV) definition. Phase B evaluated the feasibility of implementing the cone-beam CT-enabled planning process at the treatment unit. Phase C evaluated the online cone-beam CT-enabled process for the planning and treatment of patients requiring radiotherapy for bone metastases. Results: Eighty-four patients participated in this study. Phase A (n = 9) established the adequacy of cone-beam CT images for target definition. Phase B (n = 45) established the quality of treatment plans to be adequate for clinical implementation for bone metastases. When the process was applied clinically in bone metastases (Phase C), the degree of overlap between planning computed tomography (PCT) and cone-beam CT for GTV and between PCT and cone-beam CT for treatment field was 82% {+-} 11% and 97% {+-} 4%, respectively. The oncologist's decision to accept the plan under a time-pressured environment remained of high quality, with the cone-beam CT-generated treatment plan delivering at least 90% of the prescribed dose to 100% {+-} 0% of the cone-beam CT planning target volume (PTV). With the assumption that the PCT PTV is the gold-standard target, the cone-beam CT-generated treatment plan delivered at least 90% and at least 95% of dose to 98% {+-} 2% and 97% {+-} 5% of the PCT PTV, respectively. The mean time for the online planning and treatment process was 32.7 {+-} 4.0 minutes. Patient satisfaction was high, with a trend for superior satisfaction with the cone-beam CT-enabled process. Conclusions: The cone-beam

Real-time out-of-plane artifact subtraction tomosynthesis imaging using prior CT for scanning beam digital x-ray system

Energy Technology Data Exchange (ETDEWEB)

Wu, Meng, E-mail: mengwu@stanford.edu [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Fahrig, Rebecca [Department of Radiology, Stanford University, Stanford, California 94305 (United States)

2014-11-01

Purpose: The scanning beam digital x-ray system (SBDX) is an inverse geometry fluoroscopic system with high dose efficiency and the ability to perform continuous real-time tomosynthesis in multiple planes. This system could be used for image guidance during lung nodule biopsy. However, the reconstructed images suffer from strong out-of-plane artifact due to the small tomographic angle of the system. Methods: The authors propose an out-of-plane artifact subtraction tomosynthesis (OPAST) algorithm that utilizes a prior CT volume to augment the run-time image processing. A blur-and-add (BAA) analytical model, derived from the project-to-backproject physical model, permits the generation of tomosynthesis images that are a good approximation to the shift-and-add (SAA) reconstructed image. A computationally practical algorithm is proposed to simulate images and out-of-plane artifacts from patient-specific prior CT volumes using the BAA model. A 3D image registration algorithm to align the simulated and reconstructed images is described. The accuracy of the BAA analytical model and the OPAST algorithm was evaluated using three lung cancer patients’ CT data. The OPAST and image registration algorithms were also tested with added nonrigid respiratory motions. Results: Image similarity measurements, including the correlation coefficient, mean squared error, and structural similarity index, indicated that the BAA model is very accurate in simulating the SAA images from the prior CT for the SBDX system. The shift-variant effect of the BAA model can be ignored when the shifts between SBDX images and CT volumes are within ±10 mm in the x and y directions. The nodule visibility and depth resolution are improved by subtracting simulated artifacts from the reconstructions. The image registration and OPAST are robust in the presence of added respiratory motions. The dominant artifacts in the subtraction images are caused by the mismatches between the real object and the prior CT

Fast shading correction for cone beam CT in radiation therapy via sparse sampling on planning CT.

Science.gov (United States)

Shi, Linxi; Tsui, Tiffany; Wei, Jikun; Zhu, Lei

2017-05-01

The image quality of cone beam computed tomography (CBCT) is limited by severe shading artifacts, hindering its quantitative applications in radiation therapy. In this work, we propose an image-domain shading correction method using planning CT (pCT) as prior information which is highly adaptive to clinical environment. We propose to perform shading correction via sparse sampling on pCT. The method starts with a coarse mapping between the first-pass CBCT images obtained from the Varian TrueBeam system and the pCT. The scatter correction method embedded in the Varian commercial software removes some image errors but the CBCT images still contain severe shading artifacts. The difference images between the mapped pCT and the CBCT are considered as shading errors, but only sparse shading samples are selected for correction using empirical constraints to avoid carrying over false information from pCT. A Fourier-Transform-based technique, referred to as local filtration, is proposed to efficiently process the sparse data for effective shading correction. The performance of the proposed method is evaluated on one anthropomorphic pelvis phantom and 17 patients, who were scheduled for radiation therapy. (The codes of the proposed method and sample data can be downloaded from https://sites.google.com/view/linxicbct) RESULTS: The proposed shading correction substantially improves the CBCT image quality on both the phantom and the patients to a level close to that of the pCT images. On the phantom, the spatial nonuniformity (SNU) difference between CBCT and pCT is reduced from 74 to 1 HU. The root of mean square difference of SNU between CBCT and pCT is reduced from 83 to 10 HU on the pelvis patients, and from 101 to 12 HU on the thorax patients. The robustness of the proposed shading correction is fully investigated with simulated registration errors between CBCT and pCT on the phantom and mis-registration on patients. The sparse sampling scheme of our method successfully

Three-dimensional micro structured nanocomposite beams by microfluidic infiltration

International Nuclear Information System (INIS)

Lebel, L L; Paez, O A; Therriault, D; Aïssa, B; El Khakani, M A

2009-01-01

Three-dimensional (3D) micro structured beams reinforced with a single-walled carbon nanotube (C-SWNT)/polymer nanocomposite were fabricated using an approach based on the infiltration of 3D microfluidic networks. The 3D microfluidic network was first fabricated by the direct-write assembly method, which consists of the robotized deposition of fugitive ink filaments on an epoxy substrate, forming thereby a 3D micro structured scaffold. After encapsulating the 3D micro-scaffold structure with an epoxy resin, the fugitive ink was liquefied and removed, resulting in a 3D network of interconnected microchannels. This microfluidic network was then infiltrated by a polymer loaded with C-SWNTs and subsequently cured. Prior to their incorporation in the polymer matrix, the UV-laser synthesized C-SWNTs were purified, functionalized and dispersed into the matrix using a three-roll mixing mill. The final samples consist of rectangular beams having a complex 3D skeleton structure of C-SWNT/polymer nanocomposite fibers, adapted to offer better performance under flexural solicitation. Dynamic mechanical analysis in flexion showed an increase of 12.5% in the storage modulus compared to the resin infiltrated beams. The nanocomposite infiltration of microfluidic networks demonstrated here opens new prospects for the achievement of 3D reinforced micro structures

Automated segmentation of murine lung tumors in x-ray micro-CT images

Science.gov (United States)

Swee, Joshua K. Y.; Sheridan, Clare; de Bruin, Elza; Downward, Julian; Lassailly, Francois; Pizarro, Luis

2014-03-01

Recent years have seen micro-CT emerge as a means of providing imaging analysis in pre-clinical study, with in-vivo micro-CT having been shown to be particularly applicable to the examination of murine lung tumors. Despite this, existing studies have involved substantial human intervention during the image analysis process, with the use of fully-automated aids found to be almost non-existent. We present a new approach to automate the segmentation of murine lung tumors designed specifically for in-vivo micro-CT-based pre-clinical lung cancer studies that addresses the specific requirements of such study, as well as the limitations human-centric segmentation approaches experience when applied to such micro-CT data. Our approach consists of three distinct stages, and begins by utilizing edge enhancing and vessel enhancing non-linear anisotropic diffusion filters to extract anatomy masks (lung/vessel structure) in a pre-processing stage. Initial candidate detection is then performed through ROI reduction utilizing obtained masks and a two-step automated segmentation approach that aims to extract all disconnected objects within the ROI, and consists of Otsu thresholding, mathematical morphology and marker-driven watershed. False positive reduction is finally performed on initial candidates through random-forest-driven classification using the shape, intensity, and spatial features of candidates. We provide validation of our approach using data from an associated lung cancer study, showing favorable results both in terms of detection (sensitivity=86%, specificity=89%) and structural recovery (Dice Similarity=0.88) when compared against manual specialist annotation.

Accurate technique for complete geometric calibration of cone-beam computed tomography systems

International Nuclear Information System (INIS)

Cho Youngbin; Moseley, Douglas J.; Siewerdsen, Jeffrey H.; Jaffray, David A.

2005-01-01

Cone-beam computed tomography systems have been developed to provide in situ imaging for the purpose of guiding radiation therapy. Clinical systems have been constructed using this approach, a clinical linear accelerator (Elekta Synergy RP) and an iso-centric C-arm. Geometric calibration involves the estimation of a set of parameters that describes the geometry of such systems, and is essential for accurate image reconstruction. We have developed a general analytic algorithm and corresponding calibration phantom for estimating these geometric parameters in cone-beam computed tomography (CT) systems. The performance of the calibration algorithm is evaluated and its application is discussed. The algorithm makes use of a calibration phantom to estimate the geometric parameters of the system. The phantom consists of 24 steel ball bearings (BBs) in a known geometry. Twelve BBs are spaced evenly at 30 deg in two plane-parallel circles separated by a given distance along the tube axis. The detector (e.g., a flat panel detector) is assumed to have no spatial distortion. The method estimates geometric parameters including the position of the x-ray source, position, and rotation of the detector, and gantry angle, and can describe complex source-detector trajectories. The accuracy and sensitivity of the calibration algorithm was analyzed. The calibration algorithm estimates geometric parameters in a high level of accuracy such that the quality of CT reconstruction is not degraded by the error of estimation. Sensitivity analysis shows uncertainty of 0.01 deg. (around beam direction) to 0.3 deg. (normal to the beam direction) in rotation, and 0.2 mm (orthogonal to the beam direction) to 4.9 mm (beam direction) in position for the medical linear accelerator geometry. Experimental measurements using a laboratory bench Cone-beam CT system of known geometry demonstrate the sensitivity of the method in detecting small changes in the imaging geometry with an uncertainty of 0.1 mm in

Micro-computed tomography (CT) based assessment of dental regenerative therapy in the canine mandible model

Science.gov (United States)

Khobragade, P.; Jain, A.; Setlur Nagesh, S. V.; Andreana, S.; Dziak, R.; Sunkara, S. K.; Sunkara, S.; Bednarek, D. R.; Rudin, S.; Ionita, C. N.

2015-03-01

High-resolution 3D bone-tissue structure measurements may provide information critical to the understanding of the bone regeneration processes and to the bone strength assessment. Tissue engineering studies rely on such nondestructive measurements to monitor bone graft regeneration area. In this study, we measured bone yield, fractal dimension and trabecular thickness through micro-CT slices for different grafts and controls. Eight canines underwent surgery to remove a bone volume (defect) in the canine's jaw at a total of 44 different locations. We kept 11 defects empty for control and filled the remaining ones with three regenerative materials; NanoGen (NG), a FDA-approved material (n=11), a novel NanoCalcium Sulfate (NCS) material (n=11) and NCS alginate (NCS+alg) material (n=11). After a minimum of four and eight weeks, the canines were sacrificed and the jaw samples were extracted. We used a custombuilt micro-CT system to acquire the data volume and developed software to measure the bone yield, fractal dimension and trabecular thickness. The software used a segmentation algorithm based on histograms derived from volumes of interest indicated by the operator. Using bone yield and fractal dimension as indices we are able to differentiate between the control and regenerative material (p<0.005). Regenerative material NCS showed an average 63.15% bone yield improvement over the control sample, NCS+alg showed 55.55% and NanoGen showed 37.5%. The bone regeneration process and quality of bone were dependent upon the position of defect and time period of healing. This study presents one of the first quantitative comparisons using non-destructive Micro-CT analysis for bone regenerative material in a large animal with a critical defect model. Our results indicate that Micro-CT measurement could be used to monitor invivo bone regeneration studies for greater regenerative process understanding.

Application of X-ray micro-CT for micro-structural characterization of APCVD deposited SiC coatings on graphite conduit.

Science.gov (United States)

Agrawal, A K; Sarkar, P S; Singh, B; Kashyap, Y S; Rao, P T; Sinha, A

2016-02-01

SiC coatings are commonly used as oxidation protective materials in high-temperature applications. The operational performance of the coating depends on its microstructure and uniformity. This study explores the feasibility of applying tabletop X-ray micro-CT for the micro-structural characterization of SiC coating. The coating is deposited over the internal surface of pipe structured graphite fuel tube, which is a prototype of potential components of compact high-temperature reactor (CHTR). The coating is deposited using atmospheric pressure chemical vapor deposition (APCVD) and properties such as morphology, porosity, thickness variation are evaluated. Micro-structural differences in the coating caused by substrate distance from precursor inlet in a CVD reactor are also studied. The study finds micro-CT a potential tool for characterization of SiC coating during its future course of engineering. We show that depletion of reactants at larger distances causes development of larger pores in the coating, which affects its morphology, density and thickness. Copyright © 2015 Elsevier Ltd. All rights reserved.

SU-C-207A-03: Development of Proton CT Imaging System Using Thick Scintillator and CCD Camera

Energy Technology Data Exchange (ETDEWEB)

Tanaka, S; Uesaka, M [The University of Tokyo, Tokyo (Japan); Nishio, T; Tsuneda, M [Hiroshima University, Hiroshima (Japan); Matsushita, K [Rikkyo University, Tokyo (Japan); Kabuki, S [Tokai University, Isehara (Japan)

2016-06-15

Purpose: In the treatment planning of proton therapy, Water Equivalent Length (WEL), which is the parameter for the calculation of dose and the range of proton, is derived by X-ray CT (xCT) image and xCT-WEL conversion. However, about a few percent error in the accuracy of proton range calculation through this conversion has been reported. The purpose of this study is to construct a proton CT (pCT) imaging system for an evaluation of the error. Methods: The pCT imaging system was constructed with a thick scintillator and a cooled CCD camera, which acquires the two-dimensional image of integrated value of the scintillation light toward the beam direction. The pCT image is reconstructed by FBP method using a correction between the light intensity and residual range of proton beam. An experiment for the demonstration of this system was performed with 70-MeV proton beam provided by NIRS cyclotron. The pCT image of several objects reconstructed from the experimental data was evaluated quantitatively. Results: Three-dimensional pCT images of several objects were reconstructed experimentally. A finestructure of approximately 1 mm was clearly observed. The position resolution of pCT image was almost the same as that of xCT image. And the error of proton CT pixel value was up to 4%. The deterioration of image quality was caused mainly by the effect of multiple Coulomb scattering. Conclusion: We designed and constructed the pCT imaging system using a thick scintillator and a CCD camera. And the system was evaluated with the experiment by use of 70-MeV proton beam. Three-dimensional pCT images of several objects were acquired by the system. This work was supported by JST SENTAN Grant Number 13A1101 and JSPS KAKENHI Grant Number 15H04912.

Comparison of the accuracy of 3-dimensional cone-beam computed tomography and micro-computed tomography reconstructions by using different voxel sizes.

Science.gov (United States)

Maret, Delphine; Peters, Ove A; Galibourg, Antoine; Dumoncel, Jean; Esclassan, Rémi; Kahn, Jean-Luc; Sixou, Michel; Telmon, Norbert

2014-09-01

Cone-beam computed tomography (CBCT) data are, in principle, metrically exact. However, clinicians need to consider the precision of measurements of dental morphology as well as other hard tissue structures. CBCT spatial resolution, and thus image reconstruction quality, is restricted by the acquisition voxel size. The aim of this study was to assess geometric discrepancies among 3-dimensional CBCT reconstructions relative to the micro-CT reference. A total of 37 permanent teeth from 9 mandibles were scanned with CBCT 9500 and 9000 3D and micro-CT. After semiautomatic segmentation, reconstructions were obtained from CBCT acquisitions (voxel sizes 76, 200, and 300 μm) and from micro-CT (voxel size 41 μm). All reconstructions were positioned in the same plane by image registration. The topography of the geometric discrepancies was displayed by using a color map allowing the maximum differences to be located. The maximum differences were mainly found at the cervical margins and on the cusp tips or incisal edges. Geometric reconstruction discrepancies were significant at 300-μm resolution (P = .01, Wilcoxon test). To study hard tissue morphology, CBCT acquisitions require voxel sizes smaller than 300 μm. This experimental study will have to be complemented by studies in vivo that consider the conditions of clinical practice. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

TH-AB-209-01: Making Benchtop X-Ray Fluorescence Computed Tomography (XFCT) Practical for in Vivo Imaging by Integration of a Dedicated High-Performance X-Ray Source in Conjunction with Micro-CT Functionality

International Nuclear Information System (INIS)

Manohar, N; Cho, S; Reynoso, F

2016-01-01

Purpose: To make benchtop x-ray fluorescence computed tomography (XFCT) practical for routine preclinical imaging tasks with gold nanoparticles (GNPs) by deploying, integrating, and characterizing a dedicated high-performance x-ray source and addition of simultaneous micro-CT functionality. Methods: Considerable research effort is currently under way to develop a polychromatic benchtop cone-beam XFCT system capable of imaging GNPs by stimulation and detection of gold K-shell x-ray fluorescence (XRF) photons. Recently, an ad hoc high-power x-ray source was incorporated and used to image the biodistribution of GNPs within a mouse, postmortem. In the current work, a dedicated x-ray source system featuring a liquid-cooled tungsten-target x-ray tube (max 160 kVp, ∼3 kW power) was deployed. The source was operated at 125 kVp, 24 mA. The tube’s compact dimensions allowed greater flexibility for optimizing both the irradiation and detection geometries. Incident x-rays were shaped by a conical collimator and filtered by 2 mm of tin. A compact “OEM” cadmium-telluride x-ray detector was implemented for detecting XRF/scatter spectra. Additionally, a flat panel detector was installed to allow simultaneous transmission CT imaging. The performance of the system was characterized by determining the detection limit (10-second acquisition time) for inserts filled with water/GNPs at various concentrations (0 and 0.010–1.0 wt%) and embedded in a small-animal-sized phantom. The phantom was loaded with 0.5, 0.3, and 0.1 wt% inserts and imaged using XFCT and simultaneous micro-CT. Results: An unprecedented detection limit of 0.030 wt% was experimentally demonstrated, with a 33% reduction in acquisition time. The reconstructed XFCT image accurately localized the imaging inserts. Micro-CT imaging did not provide enough contrast to distinguish imaging inserts from the phantom under the current conditions. Conclusion: The system is immediately capable of in vivo preclinical XFCT

TH-AB-209-01: Making Benchtop X-Ray Fluorescence Computed Tomography (XFCT) Practical for in Vivo Imaging by Integration of a Dedicated High-Performance X-Ray Source in Conjunction with Micro-CT Functionality

Energy Technology Data Exchange (ETDEWEB)

Manohar, N; Cho, S [UT MD Anderson Cancer Center, Houston, TX (United States); Reynoso, F [UT MD Anderson Cancer Center, Houston, TX (United States); Washington University School of Medicine, St. Louis, MO (United States)

2016-06-15

Purpose: To make benchtop x-ray fluorescence computed tomography (XFCT) practical for routine preclinical imaging tasks with gold nanoparticles (GNPs) by deploying, integrating, and characterizing a dedicated high-performance x-ray source and addition of simultaneous micro-CT functionality. Methods: Considerable research effort is currently under way to develop a polychromatic benchtop cone-beam XFCT system capable of imaging GNPs by stimulation and detection of gold K-shell x-ray fluorescence (XRF) photons. Recently, an ad hoc high-power x-ray source was incorporated and used to image the biodistribution of GNPs within a mouse, postmortem. In the current work, a dedicated x-ray source system featuring a liquid-cooled tungsten-target x-ray tube (max 160 kVp, ∼3 kW power) was deployed. The source was operated at 125 kVp, 24 mA. The tube’s compact dimensions allowed greater flexibility for optimizing both the irradiation and detection geometries. Incident x-rays were shaped by a conical collimator and filtered by 2 mm of tin. A compact “OEM” cadmium-telluride x-ray detector was implemented for detecting XRF/scatter spectra. Additionally, a flat panel detector was installed to allow simultaneous transmission CT imaging. The performance of the system was characterized by determining the detection limit (10-second acquisition time) for inserts filled with water/GNPs at various concentrations (0 and 0.010–1.0 wt%) and embedded in a small-animal-sized phantom. The phantom was loaded with 0.5, 0.3, and 0.1 wt% inserts and imaged using XFCT and simultaneous micro-CT. Results: An unprecedented detection limit of 0.030 wt% was experimentally demonstrated, with a 33% reduction in acquisition time. The reconstructed XFCT image accurately localized the imaging inserts. Micro-CT imaging did not provide enough contrast to distinguish imaging inserts from the phantom under the current conditions. Conclusion: The system is immediately capable of in vivo preclinical XFCT

Micro-controller based air pressure monitoring instrumentation system using optical fibers as sensor

Science.gov (United States)

Hazarika, D.; Pegu, D. S.

2013-03-01

This paper describes a micro-controller based instrumentation system to monitor air pressure using optical fiber sensors. The principle of macrobending is used to develop the sensor system. The instrumentation system consists of a laser source, a beam splitter, two multi mode optical fibers, two Light Dependent Resistance (LDR) based timer circuits and a AT89S8252 micro-controller. The beam splitter is used to divide the laser beam into two parts and then these two beams are launched into two multi mode fibers. One of the multi mode fibers is used as the sensor fiber and the other one is used as the reference fiber. The use of the reference fiber is to eliminate the environmental effects while measuring the air pressure magnitude. The laser beams from the sensor and reference fibers are applied to two identical LDR based timer circuits. The LDR based timer circuits are interfaced to a micro-controller through its counter pins. The micro-controller samples the frequencies of the timer circuits using its counter-0 and counter-1 and the counter values are then processed to provide the measure of air pressure magnitude.

Bone Mechanical Strength Estimation from Micro X-ray CT Image

National Research Council Canada - National Science Library

Matani, A

2001-01-01

... (Bone Mineral Density), an index to evaluate the mechanical strength of the bone, does not always reflect the strength, On the other hand, micro X-ray CT has revealed the inner structure of bone, Under such circumstances...

Surface and bulk 3D analysis of natural and processed ruby using electron probe micro analyzer and X-ray micro CT scan

Energy Technology Data Exchange (ETDEWEB)

Sahoo, Rakesh K., E-mail: rakesh.materialscience@gmail.com; Singh, Saroj K.; Mishra, B.K.

2016-08-15

Highlights: • Firm linking between two advance techniques: Micro-CT and EPMA for mineral analysis. • Attempt to identify and differentiate the treated gem stone from natural counterpart. • 3D structural and surface elemental analysis of the natural gem stone. - Abstract: The change in surface compositional and bulk structural characteristics of the natural ruby stone, before and after heat treatment with lead oxide has been analyzed using two advance characterization techniques like: X-ray micro CT scan (μ-CT) and electron probe micro analyzer (EPMA). The analytical correlation between these two techniques in identification as well as in depth study of the ores and minerals before and after processing has been presented. Also, we describe the aesthetic enhancement of a low quality defective ruby stone by lead oxide filling and the sequential analysis of this ruby stone before and after treatment using these two advanced techniques to identify and to confirm the change in its aesthetic value. The cracks healing and pores filling by the metal oxide on the surface of the ruby have been analyzed using μ-CT and EPMA. Moreover, in this work we describe the advance characterization of the repaired gem stones especially ruby stones. This work will light up the path for in-depth understanding of diffusion mechanism and abstract information of impurity particles inside the minerals. Based on these observations, EPMA and micro CT are shown to be powerful tools for the identification as well as research in gem stones.

In vivo micro-CT assessment of airway remodeling in a flexible OVA-sensitized murine model of asthma.

Directory of Open Access Journals (Sweden)

Mathieu Lederlin

Full Text Available Airway remodeling is a major pathological feature of asthma. Up to now, its quantification still requires invasive methods. In this study, we aimed at determining whether in vivo micro-computed tomography (micro-CT is able to demonstrate allergen-induced airway remodeling in a flexible mouse model of asthma. Sixty Balb/c mice were challenged intranasally with ovalbumin or saline at 3 different endpoints (Days 35, 75, and 110. All mice underwent plethysmography at baseline and just prior to respiratory-gated micro-CT. Mice were then sacrificed to assess bronchoalveolar lavage and lung histology. From micro-CT images (voxel size = 46×46×46 µm, the numerical values of total lung attenuation, peribronchial attenuation (PBA, and PBA normalized by total lung attenuation were extracted. Each parameter was compared between OVA and control mice and correlation coefficients were calculated between micro-CT and histological data. As compared to control animals, ovalbumin-sensitized mice exhibited inflammation alone (Day 35, remodeling alone (Day 110 or both inflammation and remodeling (Day 75. Normalized PBA was significantly greater in mice exhibiting bronchial remodeling either alone or in combination with inflammation. Normalized PBA correlated with various remodeling markers such as bronchial smooth muscle size or peribronchial fibrosis. These findings suggest that micro-CT may help monitor remodeling non-invasively in asthmatic mice when testing new drugs targeting airway remodeling in pre-clinical studies.

Cone beam CT findings of retromolar canals: Report of cases and literature review

Energy Technology Data Exchange (ETDEWEB)

Han, Sang Sun [Dept. of Dental Hygiene, Eulji University, Seongnam (Korea, Republic of); Park, Chang Seo [Dept. of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul (Korea, Republic of)

2013-12-15

A retromolar canal is an anatomical variation in the mandible. As it includes the neurovascular bundle, local anesthetic insufficiency can occur, and an injury of the retromolar canal during dental surgery in the mandible may result in excessive bleeding, paresthesia, and traumatic neuroma. Using imaging analysis software, we evaluated the cone-beam computed tomography (CT) images of two Korean patients who presented with retromolar canals. Retromolar canals were detectable on the sagittal and cross-sectional images of cone-beam CT, but not on the panoramic radiographs of the patients. Therefore, the clinician should pay particular attention to the identification of retromolar canals by preoperative radiographic examination, and additional cone beam CT scanning would be recommended.

Cone beam CT findings of retromolar canals: Report of cases and literature review

International Nuclear Information System (INIS)

Han, Sang Sun; Park, Chang Seo

2013-01-01

A retromolar canal is an anatomical variation in the mandible. As it includes the neurovascular bundle, local anesthetic insufficiency can occur, and an injury of the retromolar canal during dental surgery in the mandible may result in excessive bleeding, paresthesia, and traumatic neuroma. Using imaging analysis software, we evaluated the cone-beam computed tomography (CT) images of two Korean patients who presented with retromolar canals. Retromolar canals were detectable on the sagittal and cross-sectional images of cone-beam CT, but not on the panoramic radiographs of the patients. Therefore, the clinician should pay particular attention to the identification of retromolar canals by preoperative radiographic examination, and additional cone beam CT scanning would be recommended.

Use of Large Surface MicroChannel Plates for the Tagging of Intermediate Energy Exotic Beams

Energy Technology Data Exchange (ETDEWEB)

Lombardo, I., E-mail: ilombardo@lns.infn.it [Dipartimento di Fisica, Universita di Catania, Catania (Italy); INFN Laboratori Nazionali del Sud, Catania (Italy); Amorini, F. [INFN Laboratori Nazionali del Sud, Catania (Italy); Cardella, G. [INFN, Sezione di Catania, Catania (Italy); Cavallaro, S. [Dipartimento di Fisica, Universita di Catania, Catania (Italy); INFN Laboratori Nazionali del Sud, Catania (Italy); De Filippo, E. [INFN, Sezione di Catania, Catania (Italy); Geraci, E.; Grassi, L. [Dipartimento di Fisica, Universita di Catania, Catania (Italy); INFN, Sezione di Catania, Catania (Italy); La Guidara, E. [INFN, Sezione di Catania, Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lanzalone, G. [INFN Laboratori Nazionali del Sud, Catania (Italy); Libera Universita Kore, Enna (Italy); Pagano, A.; Papa, M.; Pirrone, S. [INFN, Sezione di Catania, Catania (Italy); Politi, G. [Dipartimento di Fisica, Universita di Catania, Catania (Italy); INFN, Sezione di Catania, Catania (Italy); Porto, F.; Rizzo, F.; Russotto, P. [Dipartimento di Fisica, Universita di Catania, Catania (Italy); INFN Laboratori Nazionali del Sud, Catania (Italy); Verde, G. [INFN, Sezione di Catania, Catania (Italy); Vigilante, M. [INFN, Sezione di Napoli and Dipartimento di Fisica, Universita Federico II di Napoli (Italy)

2011-06-15

We show the properties of the tagging system for exotic beams coupled to the CHIMERA detector. In particular, the characteristics of a newly developed large surface MicroChannel Plate will be discussed. Timing and efficiency of this instrument have been investigated. Preliminary results of tests performed with radioactive beams and alpha sources are presented.

Monte Carlo simulations of the dose from imaging with GE eXplore 120 micro-CT using GATE

Energy Technology Data Exchange (ETDEWEB)

Bretin, Florian; Bahri, Mohamed Ali; Luxen, André; Phillips, Christophe; Plenevaux, Alain; Seret, Alain, E-mail: aseret@ulg.ac.be [Cyclotron Research Centre, University of Liège, Sart Tilman B30, Liège 4000 (Belgium)

2015-10-15

Purpose: Small animals are increasingly used as translational models in preclinical imaging studies involving microCT, during which the subjects can be exposed to large amounts of radiation. While the radiation levels are generally sublethal, studies have shown that low-level radiation can change physiological parameters in mice. In order to rule out any influence of radiation on the outcome of such experiments, or resulting deterministic effects in the subjects, the levels of radiation involved need to be addressed. The aim of this study was to investigate the radiation dose delivered by the GE eXplore 120 microCT non-invasively using Monte Carlo simulations in GATE and to compare results to previously obtained experimental values. Methods: Tungsten X-ray spectra were simulated at 70, 80, and 97 kVp using an analytical tool and their half-value layers were simulated for spectra validation against experimentally measured values of the physical X-ray tube. A Monte Carlo model of the microCT system was set up and four protocols that are regularly applied to live animal scanning were implemented. The computed tomography dose index (CTDI) inside a PMMA phantom was derived and multiple field of view acquisitions were simulated using the PMMA phantom, a representative mouse and rat. Results: Simulated half-value layers agreed with experimentally obtained results within a 7% error window. The CTDI ranged from 20 to 56 mGy and closely matched experimental values. Derived organ doses in mice reached 459 mGy in bones and up to 200 mGy in soft tissue organs using the highest energy protocol. Dose levels in rats were lower due to the increased mass of the animal compared to mice. The uncertainty of all dose simulations was below 14%. Conclusions: Monte Carlo simulations proved a valuable tool to investigate the 3D dose distribution in animals from microCT. Small animals, especially mice (due to their small volume), receive large amounts of radiation from the GE eXplore 120

An energy-based beam hardening model in tomography

International Nuclear Information System (INIS)

Casteele, E van de; Dyck, D van; Sijbers, J; Raman, E

2002-01-01

As a consequence of the polychromatic x-ray source, used in micro-computer tomography (μCT) and in medical CT, the attenuation is no longer a linear function of absorber thickness. If this nonlinear beam hardening effect is not compensated, the reconstructed images will be corrupted by cupping artefacts. In this paper, a bimodal energy model for the detected energy spectrum is presented, which can be used for reduction of artefacts caused by beam hardening in well-specified conditions. Based on the combination of the spectrum of the source and the detector efficiency, the assumption is made that there are two dominant energies which can describe the system. The validity of the proposed model is examined by fitting the model to the experimental datapoints obtained on a microtomograph for different materials and source voltages

Analysis of the enamel hypoplasia using micro-CT scanner versus classical method.

Science.gov (United States)

Marchewka, Justyna; Skrzat, Janusz; Wróbel, Andrzej

2014-01-01

This article demonstrates the use of micro-CT scanning of the teeth surface for recognizing and evaluating severity of the enamel hypoplasia. To test capabilities of the microtomography versus classical method of evaluation hypoplastic defects of the enamel we selected two human teeth (C, M(2)) showing different types of enamel hypoplasia: linear, pits, and groove. Examined samples derive from archeological material dated on XVII-XVIII AD and excavated in Poland. In the current study we proved that micro-CT scanning is a powerful technique not only for imaging all kinds of the enamel hypoplasia but also allows to perform accurate measurements of the enamel defects. We figure out that contrary to the classical method of scoring enamel defects, the micro-computed tomography yields adequate data which serve for estimating the length of stress episode and length of interval between them.

The extensor carpi ulnaris pseudolesion: evaluation with microCT, histology, and MRI

International Nuclear Information System (INIS)

Ali, Sayed; Cunningham, Ryan; Mohamed, Feroze; Amin, Mamta; Popoff, Steven N.; Barbe, Mary F.

2015-01-01

To determine if magic angle plays a role in apparent central increased signal intensity of the distal extensor carpi ulnaris tendon (ECU) on MRI, to see if histologic findings of tendon degeneration are associated with increased T1 or T2 tendon signal on MR imaging, and to determine the prevalence of the ECU ''pseudolesion''. A standard 3 Tesla protocol was utilized to scan ten cadaveric wrists. A 40 mm length of 10 ECU and four extensor carpi radialis brevis (ECRB) tendons were immersion fixed before microCT scanning. Staining with Alcian blue, Masson's trichrome and Safranin O was performed before light microscopy. Fifty clinical wrist MRIs were also reviewed for the presence of increased T1 and/or T2 signal. Central increased T1 and/or T2 signal was observed in 9 of 10 cadaveric ECU tendons, but not in ECRB tendons. MicroCT and histology showed inter-tendinous matrix between the two distal heads of the ECU. Increased mucoid degeneration correlated with increased MRI signal intensity. The tendon fibers were at a maximum of 8.39 to the longitudinal axis on microCT. Clinical MRIs showed increased T1 signal in 6 %, increased T2 signal in 8 %, increased T1 and T2 signal in 80 %, and 6 % showing no increased signal. Central increased T1 and/or T2 signal in the ECU tendon indicates the presence of normal inter-tendinous ground substance, with increased proteoglycan content (mucoid degeneration) responsible for increased signal intensity. None of the fibers were shown on microCT to approach the magic angle. (orig.)

The extensor carpi ulnaris pseudolesion: evaluation with microCT, histology, and MRI

Energy Technology Data Exchange (ETDEWEB)

Ali, Sayed; Cunningham, Ryan; Mohamed, Feroze [Temple University Hospital, Department of Radiology, Philadelphia, PA (United States); Amin, Mamta; Popoff, Steven N.; Barbe, Mary F. [Temple University School of Medicine, Department of Anatomy, Philadelphia, PA (United States)

2015-12-15

To determine if magic angle plays a role in apparent central increased signal intensity of the distal extensor carpi ulnaris tendon (ECU) on MRI, to see if histologic findings of tendon degeneration are associated with increased T1 or T2 tendon signal on MR imaging, and to determine the prevalence of the ECU ''pseudolesion''. A standard 3 Tesla protocol was utilized to scan ten cadaveric wrists. A 40 mm length of 10 ECU and four extensor carpi radialis brevis (ECRB) tendons were immersion fixed before microCT scanning. Staining with Alcian blue, Masson's trichrome and Safranin O was performed before light microscopy. Fifty clinical wrist MRIs were also reviewed for the presence of increased T1 and/or T2 signal. Central increased T1 and/or T2 signal was observed in 9 of 10 cadaveric ECU tendons, but not in ECRB tendons. MicroCT and histology showed inter-tendinous matrix between the two distal heads of the ECU. Increased mucoid degeneration correlated with increased MRI signal intensity. The tendon fibers were at a maximum of 8.39 to the longitudinal axis on microCT. Clinical MRIs showed increased T1 signal in 6 %, increased T2 signal in 8 %, increased T1 and T2 signal in 80 %, and 6 % showing no increased signal. Central increased T1 and/or T2 signal in the ECU tendon indicates the presence of normal inter-tendinous ground substance, with increased proteoglycan content (mucoid degeneration) responsible for increased signal intensity. None of the fibers were shown on microCT to approach the magic angle. (orig.)

Fabrication of phosphor micro-grids using proton beam lithography

International Nuclear Information System (INIS)

Rossi, Paolo; Antolak, Arlyn J.; Provencio, Paula Polyak; Doyle, Barney Lee; Malmqvist, Klas; Hearne, Sean Joseph; Nilsson, Christer; Kristiansson, Per; Wegden, Marie; Elfman, Mikael; Pallon, Jan; Auzelyte, Vaida

2005-01-01

A new nuclear microscopy technique called ion photon emission microscopy or IPEM was recently invented. IPEM allows analysis involving single ions, such as ion beam induced charge (IBIC) or single event upset (SEU) imaging using a slightly modified optical microscope. The spatial resolution of IPEM is currently limited to more than 10 (micro)m by the scattering and reflection of ion-induced photons, i.e. light blooming or spreading, in the ionoluminescent phosphor layer. We are developing a 'Microscopic Gridded Phosphor' (also called Black Matrix) where the phosphor nanocrystals are confined within the gaps of a micrometer scale opaque grid, which limits the amount of detrimental light blooming. MeV-energy proton beam lithography is ideally suited to lithographically form masks for the grid because of high aspect ratio, pattern density and sub-micron resolution of this technique. In brief, the fabrication of the grids was made in the following manner: (1) a MeV proton beam focused to 1.5-2 (micro)m directly fabricated a matrix of pillars in a 15 (micro)m thick SU-8 lithographic resist; (2) 7:1 aspect ratio pillars were then formed by developing the proton exposed area; (3) Ni (Au) was electrochemically deposited onto Cu-coated Si from a sulfamate bath (or buffered CN bath); (4) the SU-8 pillars were removed by chemical etching; finally (5) the metal micro-grid was freed from its substrate by etching the underlying Cu layer. Our proposed metal micro-grids promise an order-of-magnitude improvement in the resolution of IPEM.

Micro-Bunched Beam Production at FAST for Narrow Band THz Generation Using a Slit-Mask

Energy Technology Data Exchange (ETDEWEB)

Hyun, J. [Sokendai, Tsukuba; Crawford, D. [Fermilab; Edstrom Jr, D. [Fermilab; Ruan, J. [Fermilab; Santucci, J. [Fermilab; Thurman-Keup, R. [Fermilab; Sen, T. [Fermilab; Thangaraj, J. C. [Fermilab

2018-04-01

We discuss simulations and experiments on creating micro-bunch beams for generating narrow band THz radiation at the Fermilab Accelerator Science and Technology (FAST) facility. The low-energy electron beamline at FAST consists of a photoinjector-based RF gun, two Lband superconducting accelerating cavities, a chicane, and a beam dump. The electron bunches are lengthened with cavity phases set off-crest for better longitudinal separation and then micro-bunched with a slit-mask installed in the chicane. We carried out the experiments with 30 MeV electron beams and detected signals of the micro-bunching using a skew quadrupole magnet in the chicane. In this paper, the details of micro-bunch beam production, the detection of micro-bunching and comparison with simulations are described.

The use of 2D pixel detectors in micro- and nano-CT applications

International Nuclear Information System (INIS)

Dierick, Manuel; Hoorebeke, Luc van; Jacobs, Patric; Masschaele, Bert; Vlassenbroeck, Jelle; Cnudde, Veerle; De Witte, Yoni

2008-01-01

Computed tomography or CT is a non-destructive imaging technique that uses penetrating radiation (mostly X-rays) to visualize the internal structure of a sample. The best-known example is the medical CT scanner, which has become a standard diagnostic tool in medicine, providing detailed views of the body with spatial resolutions below 1 mm. In recent years another type of CT scanner has been developed for mostly industrial and scientific applications, namely micro-CT scanners. These reached spatial resolutions down to a few microns. During 2005 the Radiation Physics research group (Department of Subatomic and Radiation Physics) and the Sedimentary Geology and Engineering Geology research group (Department of Geology and Soil Science) of the Ghent University jointly developed a modular micro-CT setup. The two main goals were to achieve a spatial resolution below 1 μm and to have a very versatile tool providing high-quality images. The source is a dual-head X-ray tube with a transmission type head with a nominal focal spot size of 900 nm below 40 kV tube voltage for high-resolution applications and a directional high-power head (up to 160 kV, up to 150 W), which enables scanning of larger samples. A six-axis sample manipulator system was assembled. The crucial component in this is an ultra-high-precision air-bearing rotation stage to keep all motion errors during rotation well below 1 μm. Depending on the application we have the choice between a number of detectors, each with its own advantages in terms of size, pixel resolution and energy sensitivity

High Dose MicroCT Does Not Contribute Toward Improved MicroPET/CT Image Quantitative Accuracy and Can Limit Longitudinal Scanning of Small Animals

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Wendy A. McDougald

2017-10-01

Full Text Available Obtaining accurate quantitative measurements in preclinical Positron Emission Tomography/Computed Tomography (PET/CT imaging is of paramount importance in biomedical research and helps supporting efficient translation of preclinical results to the clinic. The purpose of this study was two-fold: (1 to investigate the effects of different CT acquisition protocols on PET/CT image quality and data quantification; and (2 to evaluate the absorbed dose associated with varying CT parameters.Methods: An air/water quality control CT phantom, tissue equivalent material phantom, an in-house 3D printed phantom and an image quality PET/CT phantom were imaged using a Mediso nanoPET/CT scanner. Collected data was analyzed using PMOD software, VivoQuant software and National Electric Manufactures Association (NEMA software implemented by Mediso. Measured Hounsfield Unit (HU in collected CT images were compared to the known HU values and image noise was quantified. PET recovery coefficients (RC, uniformity and quantitative bias were also measured.Results: Only less than 2 and 1% of CT acquisition protocols yielded water HU values < −80 and air HU values < −840, respectively. Four out of 11 CT protocols resulted in more than 100 mGy absorbed dose. Different CT protocols did not impact PET uniformity and RC, and resulted in <4% overall bias relative to expected radioactive concentration.Conclusion: Preclinical CT protocols with increased exposure times can result in high absorbed doses to the small animals. These should be avoided, as they do not contributed toward improved microPET/CT image quantitative accuracy and could limit longitudinal scanning of small animals.

The cutting edge - Micro-CT for quantitative toolmark analysis of sharp force trauma to bone.

Science.gov (United States)

Norman, D G; Watson, D G; Burnett, B; Fenne, P M; Williams, M A

2018-02-01

Toolmark analysis involves examining marks created on an object to identify the likely tool responsible for creating those marks (e.g., a knife). Although a potentially powerful forensic tool, knife mark analysis is still in its infancy and the validation of imaging techniques as well as quantitative approaches is ongoing. This study builds on previous work by simulating real-world stabbings experimentally and statistically exploring quantitative toolmark properties, such as cut mark angle captured by micro-CT imaging, to predict the knife responsible. In Experiment 1 a mechanical stab rig and two knives were used to create 14 knife cut marks on dry pig ribs. The toolmarks were laser and micro-CT scanned to allow for quantitative measurements of numerous toolmark properties. The findings from Experiment 1 demonstrated that both knives produced statistically different cut mark widths, wall angle and shapes. Experiment 2 examined knife marks created on fleshed pig torsos with conditions designed to better simulate real-world stabbings. Eight knives were used to generate 64 incision cut marks that were also micro-CT scanned. Statistical exploration of these cut marks suggested that knife type, serrated or plain, can be predicted from cut mark width and wall angle. Preliminary results suggest that knives type can be predicted from cut mark width, and that knife edge thickness correlates with cut mark width. An additional 16 cut marks walls were imaged for striation marks using scanning electron microscopy with results suggesting that this approach might not be useful for knife mark analysis. Results also indicated that observer judgements of cut mark shape were more consistent when rated from micro-CT images than light microscopy images. The potential to combine micro-CT data, medical grade CT data and photographs to develop highly realistic virtual models for visualisation and 3D printing is also demonstrated. This is the first study to statistically explore simulated

Nonlinear behavior of capacitive micro-beams based on strain gradient theory

International Nuclear Information System (INIS)

Fathalilou, Mohammad; Sadeghi, Morteza; Rezazadeh, Ghader

2014-01-01

This paper studies the size dependent behavior of materials in MEMS structures. This behavior becomes noticeable for a structure when the characteristic size such as thickness or diameter is close to its internal length-scale parameter and is insignificant for the high ratio of the characteristic size to the length-scale parameter, which is the case of the silicon base micro-beams. However, in some types of micro-beams like gold or nickel bases, the size dependent effect cannot be overlooked. In such cases, ignoring this behavior in modeling will lead to incorrect results. Some previous researchers have applied classic beam theory on their models and imposed a considerable hypothetical value of residual stress to match their theoretical results with the experimental ones. The equilibrium positions or fixed points of the gold and nickel micro-beams are obtained and shown that for a given DC voltage, there is a considerable difference between the obtained fixed points using classic beam theory, modified couple stress theory, and modified strain gradient theory. In addition, it is shown that the calculated static and dynamic pull-in voltages using higher order theories are much closer to the experimental results and are higher several times than those obtained by classic beam theory.

Minimizing image noise in on-board CT reconstruction using both kilovoltage and megavoltage beam projections

International Nuclear Information System (INIS)

Zhang Junan; Yin Fangfang

2007-01-01

We studied a recently proposed aggregated CT reconstruction technique which combines the complementary advantages of kilovoltage (kV) and megavoltage (MV) x-ray imaging. Various phantoms were imaged to study the effects of beam orientations and geometry of the imaging object on image quality of reconstructed CT. It was shown that the quality of aggregated CT was correlated with both kV and MV beam orientations and the degree of this correlation depended upon the geometry of the imaging object. The results indicated that the optimal orientations were those when kV beams pass through the thinner portion and MV beams pass through the thicker portion of the imaging object. A special preprocessing procedure was also developed to perform contrast conversions between kV and MV information prior to image reconstruction. The performance of two reconstruction methods, one filtered backprojection method and one iterative method, were compared. The effects of projection number, beam truncation, and contrast conversion on the CT image quality were investigated

Nondestructive Analysis of Astromaterials by Micro-CT and Micro-XRF Analysis for PET Examination

Science.gov (United States)

Zeigler, R. A.; Righter, K.; Allen, C. C.

2013-01-01

An integral part of any sample return mission is the initial description and classification of returned samples by the preliminary examination team (PET). The goal of the PET is to characterize and classify returned samples and make this information available to the larger research community who then conduct more in-depth studies on the samples. The PET tries to minimize the impact their work has on the sample suite, which has in the past limited the PET work to largely visual, nonquantitative measurements (e.g., optical microscopy). More modern techniques can also be utilized by a PET to nondestructively characterize astromaterials in much more rigorous way. Here we discuss our recent investigations into the applications of micro-CT and micro-XRF analyses with Apollo samples and ANSMET meteorites and assess the usefulness of these techniques in future PET. Results: The application of micro computerized tomography (micro-CT) to astromaterials is not a new concept. The technique involves scanning samples with high-energy x-rays and constructing 3-dimensional images of the density of materials within the sample. The technique can routinely measure large samples (up to approx. 2700 cu cm) with a small individual voxel size (approx. 30 cu m), and has the sensitivity to distinguish the major rock forming minerals and identify clast populations within brecciated samples. We have recently run a test sample of a terrestrial breccia with a carbonate matrix and multiple igneous clast lithologies. The test results are promising and we will soon analyze a approx. 600 g piece of Apollo sample 14321 to map out the clast population within the sample. Benchtop micro x-ray fluorescence (micro-XRF) instruments can rapidly scan large areas (approx. 100 sq cm) with a small pixel size (approx. 25 microns) and measure the (semi) quantitative composition of largely unprepared surfaces for all elements between Be and U, often with sensitivity on the order of a approx. 100 ppm. Our recent

Improved quantification in single-pinhole and multiple-pinhole SPECT using micro-CT information

International Nuclear Information System (INIS)

Vanhove, Christian; Bossuyt, Axel; Defrise, Michel; Lahoutte, Tony

2009-01-01

The purpose of this study was to demonstrate the feasibility of accurate quantification in pinhole SPECT using micro-CT information. Pinhole SPECT scans were performed using a clinical dual-head gamma camera. Each pinhole SPECT scan was followed by a micro-CT acquisition. Functional and anatomical images were coregistered using six point sources visible with both modalities. Pinhole SPECT images were reconstructed iteratively. Attenuation correction was based on micro-CT information. Scatter correction was based on dual and triple-energy window methods. Phantom and animal experiments were performed. A phantom containing nine vials was filled with different concentrations of 99m Tc. Three vials were also filled with CT contrast agent to increase attenuation. Activity concentrations measured on the pinhole SPECT images were compared with activity concentrations measured by the dose calibrator. In addition, 11 mice were injected with 99m Tc-labelled Nanobodies. After acquiring functional and anatomical images, the animals were killed and the liver activity was measured using a gamma-counter. Activity concentrations measured on the reconstructed images were compared with activity concentrations measured with the gamma counter. The phantom experiments demonstrated an average error of -27.3 ± 15.9% between the activity concentrations measured on the uncorrected pinhole SPECT images and in the dose calibrator. This error decreased significantly to -0.1 ± 7.3% when corrections were applied for nonuniform attenuation and scatter. The animal experiment revealed an average error of -18.4 ± 11.9% between the activity concentrations measured on the uncorrected pinhole SPECT images and measured with the gamma counter. This error decreased to -7.9 ± 10.4% when attenuation and scatter correction was applied. Attenuation correction obtained from micro-CT data in combination with scatter correction allows accurate quantification in pinhole SPECT. (orig.)

Five-dimensional motion compensation for respiratory and cardiac motion with cone-beam CT of the thorax region

Science.gov (United States)

Sauppe, Sebastian; Hahn, Andreas; Brehm, Marcus; Paysan, Pascal; Seghers, Dieter; Kachelrieß, Marc

2016-03-01

We propose an adapted method of our previously published five-dimensional (5D) motion compensation (MoCo) algorithm1, developed for micro-CT imaging of small animals, to provide for the first time motion artifact-free 5D cone-beam CT (CBCT) images from a conventional flat detector-based CBCT scan of clinical patients. Image quality of retrospectively respiratory- and cardiac-gated volumes from flat detector CBCT scans is deteriorated by severe sparse projection artifacts. These artifacts further complicate motion estimation, as it is required for MoCo image reconstruction. For high quality 5D CBCT images at the same x-ray dose and the same number of projections as todays 3D CBCT we developed a double MoCo approach based on motion vector fields (MVFs) for respiratory and cardiac motion. In a first step our already published four-dimensional (4D) artifact-specific cyclic motion-compensation (acMoCo) approach is applied to compensate for the respiratory patient motion. With this information a cyclic phase-gated deformable heart registration algorithm is applied to the respiratory motion-compensated 4D CBCT data, thus resulting in cardiac MVFs. We apply these MVFs on double-gated images and thereby respiratory and cardiac motion-compensated 5D CBCT images are obtained. Our 5D MoCo approach processing patient data acquired with the TrueBeam 4D CBCT system (Varian Medical Systems). Our double MoCo approach turned out to be very efficient and removed nearly all streak artifacts due to making use of 100% of the projection data for each reconstructed frame. The 5D MoCo patient data show fine details and no motion blurring, even in regions close to the heart where motion is fastest.

Study of residual stresses in CT test specimens welded by electron beam

Science.gov (United States)

Papushkin, I. V.; Kaisheva, D.; Bokuchava, G. D.; Angelov, V.; Petrov, P.

2018-03-01

The paper reports result of residual stress distribution studies in CT specimens reconstituted by electron beam welding (EBW). The main aim of the study is evaluation of the applicability of the welding technique for CT specimens’ reconstitution. Thus, the temperature distribution during electron beam welding of a CT specimen was calculated using Green’s functions and the residual stress distribution was determined experimentally using neutron diffraction. Time-of-flight neutron diffraction experiments were performed on a Fourier stress diffractometer at the IBR-2 fast pulsed reactor in FLNP JINR (Dubna, Russia). The neutron diffraction data estimates yielded a maximal stress level of ±180 MPa in the welded joint.

Serial micro-CT assessment of the therapeutic effects of rosiglitazone in a bleomycin-induced lung fibrosis mouse model

Energy Technology Data Exchange (ETDEWEB)

Choi, Eun Jung; Jin, Gong Yong; Bok, Se Mi; Han, Young Min; Lee, Young Sun; Jung, Myung Ja; Kwon, Keun Sang [Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital, Institute for Medical Sciences, Jeonju (Korea, Republic of)

2014-08-15

The aim of this study was to assess the therapeutic effects of rosiglitazone with serial micro-CT findings before and after rosiglitazone administration in a lung fibrosis mouse model induced with bleomycin. We instilled the bleomycin solution directly into the trachea in twenty mice (female, C57BL/6 mice). After the instillation with bleomycin, mice were closely observed for 3 weeks and then all mice were scanned using micro-CT without sacrifice. At 3 weeks, the mice were treated with rosiglitazone on days 21 to 27 if they had abnormal CT findings (n = 9, 45%). For the mice treated with rosiglitazone, we performed micro-CT with mouse sacrifice 2 weeks after the rosiglitazone treatment completion. We assessed the abnormal CT findings (ground glass attenuation, consolidation, bronchiectasis, reticular opacity, and honeycombing) using a five-point scale at 3 and 6 weeks using Wilcoxon-signed ranked test. The micro-CT findings were correlated with the histopathologic results. One out of nine (11.1%) mice improved completely. In terms of consolidation, all mice (100%) showed marked decrease from 3.1 ± 1.4 at 3 weeks to 0.9 ± 0.9 at 6 weeks (p = 0.006). At 6 weeks, mild bronchiectasis (n = 6, 66.7%), mild reticular opacity (n 7, 77.8%) and mild honeycomb patterns (n = 3, 33.3%) appeared. A serial micro-CT enables the evaluation of drug effects in a lung fibrosis mouse model.

Imaging the Aqueous Humor Outflow Pathway in Human Eyes by Three-dimensional Micro-computed Tomography (3D micro-CT)

Energy Technology Data Exchange (ETDEWEB)

C Hann; M Bentley; A Vercnocke; E Ritman; M Fautsch

2011-12-31

The site of outflow resistance leading to elevated intraocular pressure in primary open-angle glaucoma is believed to be located in the region of Schlemm's canal inner wall endothelium, its basement membrane and the adjacent juxtacanalicular tissue. Evidence also suggests collector channels and intrascleral vessels may have a role in intraocular pressure in both normal and glaucoma eyes. Traditional imaging modalities limit the ability to view both proximal and distal portions of the trabecular outflow pathway as a single unit. In this study, we examined the effectiveness of three-dimensional micro-computed tomography (3D micro-CT) as a potential method to view the trabecular outflow pathway. Two normal human eyes were used: one immersion fixed in 4% paraformaldehyde and one with anterior chamber perfusion at 10 mmHg followed by perfusion fixation in 4% paraformaldehyde/2% glutaraldehyde. Both eyes were postfixed in 1% osmium tetroxide and scanned with 3D micro-CT at 2 {mu}m or 5 {mu}m voxel resolution. In the immersion fixed eye, 24 collector channels were identified with an average orifice size of 27.5 {+-} 5 {mu}m. In comparison, the perfusion fixed eye had 29 collector channels with a mean orifice size of 40.5 {+-} 13 {mu}m. Collector channels were not evenly dispersed around the circumference of the eye. There was no significant difference in the length of Schlemm's canal in the immersed versus the perfused eye (33.2 versus 35.1 mm). Structures, locations and size measurements identified by 3D micro-CT were confirmed by correlative light microscopy. These findings confirm 3D micro-CT can be used effectively for the non-invasive examination of the trabecular meshwork, Schlemm's canal, collector channels and intrascleral vasculature that comprise the distal outflow pathway. This imaging modality will be useful for non-invasive study of the role of the trabecular outflow pathway as a whole unit.

Evaluation of physicochemical properties of root-end filling materials using conventional and Micro-CT tests

Directory of Open Access Journals (Sweden)

Fernanda Ferrari Esteves TORRES

Full Text Available Abstract Objective To evaluate solubility, dimensional stability, filling ability and volumetric change of root-end filling materials using conventional tests and new Micro-CT-based methods. Material and Methods Solubility (loss of mass after 7 and 30 days, and dimensional stability (in mm were evaluated in accordance with Carvalho-Junior, et al. 7 (2007. The filling ability and volumetric change (in mm3 were evaluated by Micro-CT (Bruker-MicroCT, Kontich, Belgium using resin models with cavities 3 mm deep and 1 mm in diameter. The cavities were filled with materials to evaluate filling ability, and then scanned by Micro-CT. After 7 and 30 days immersed in distilled water, the filled cavities were scanned again to evaluate the volumetric change. MTA Angelus (MTA, Biodentine (BIO and zinc oxide-eugenol cement (ZOE were evaluated. Data were submitted to analysis of variance (ANOVA and Tukey's test with 5% significance level. Results The results suggested correlated or complementary data between the proposed tests. At 7 days, BIO showed higher solubility and at 30 days, showed higher volumetric change in comparison with MTA (p0.05 at 7 days. At 30 days, they presented similar solubility. BIO and MTA showed higher dimensional stability than ZOE (p<0.05. ZOE and BIO showed higher filling ability (p<0.05. Conclusions ZOE presented a higher dimensional change, and BIO had greater solubility after 7 days. BIO presented filling ability and dimensional stability, but greater volumetric change than MTA after 30 days. Micro-CT can provide important data on the physicochemical properties of materials complementing conventional tests.

Automated planning of breast radiotherapy using cone beam CT imaging

International Nuclear Information System (INIS)

Amit, Guy; Purdie, Thomas G.

2015-01-01

Purpose: Develop and clinically validate a methodology for using cone beam computed tomography (CBCT) imaging in an automated treatment planning framework for breast IMRT. Methods: A technique for intensity correction of CBCT images was developed and evaluated. The technique is based on histogram matching of CBCT image sets, using information from “similar” planning CT image sets from a database of paired CBCT and CT image sets (n = 38). Automated treatment plans were generated for a testing subset (n = 15) on the planning CT and the corrected CBCT. The plans generated on the corrected CBCT were compared to the CT-based plans in terms of beam parameters, dosimetric indices, and dose distributions. Results: The corrected CBCT images showed considerable similarity to their corresponding planning CTs (average mutual information 1.0±0.1, average sum of absolute differences 185 ± 38). The automated CBCT-based plans were clinically acceptable, as well as equivalent to the CT-based plans with average gantry angle difference of 0.99°±1.1°, target volume overlap index (Dice) of 0.89±0.04 although with slightly higher maximum target doses (4482±90 vs 4560±84, P < 0.05). Gamma index analysis (3%, 3 mm) showed that the CBCT-based plans had the same dose distribution as plans calculated with the same beams on the registered planning CTs (average gamma index 0.12±0.04, gamma <1 in 99.4%±0.3%). Conclusions: The proposed method demonstrates the potential for a clinically feasible and efficient online adaptive breast IMRT planning method based on CBCT imaging, integrating automation

Whispering Gallery Mode Resonances from Ge Micro-Disks on Suspended Beams

Directory of Open Access Journals (Sweden)

Abdelrahman Zaher Al-Attili

2015-05-01

Full Text Available Ge is considered to be one of the most promising materials for realizing full monolithic integration of a light source on a silicon (Si photonic chip. Tensile-strain is required to convert Ge into an optical gain material and to reduce the pumping required for population inversion. Several methods of strain application to Ge are proposed in literature, of which the use of free-standing beams fabricated by micro-electro-mechanical systems (MEMS processes are capable of delivering very high strain values. However, it is challenging to make an optical cavity within free-standing Ge beams, and here, we demonstrate the fabrication of a simple cavity while imposing tensile strain by suspension using Ge-On-Insulator (GOI wafers. Ge micro-disks are made on top of suspended SiO$_{2}$ beams by partially removing the supporting Si substrate. According to Raman spectroscopy, a slight tensile strain was applied to the Ge disks through the bending of the SiO2 beams. Whispering-Gallery-Mode (WGM resonances were observed from a disk with a diameter of 3um, consistent with the finite-domain time-difference simulations. The quality (Q factor was 192, and upon increasing the pumping power, the Q-factor was degraded due to the red-shift of Ge direct-gap absorption edge caused by heating.

Cell micro-patterning by atom beam exposure

International Nuclear Information System (INIS)

Adachi, Taiji; Kajita, Fumiaki; Sato, Katsuya; Matsumoto, Koshi; Tagawa, Masahiro

2003-01-01

This study aimed to develop a new cell micro-patterning method by controlling material surface affinity of the cell using atomic oxygen beam exposure. Surfaces of low-density polyethylene (LDPE) and tetrafluoroethylene-hexafluoropropylene (FEP) were exposed to the atomic oxygen beam. On the LDPE surface, the roughness measured by atomic force microscopy (AFM) did not change much, however, the oxygen concentration on the surface measured by X-ray photoelectron spectroscopy (XPS) significantly increased that resulted in increase in wettability. Contrary to this, on the FEP surface, the oxygen concentration showed no significant change, but roughness of the surface remarkably increased and the wettability decreased. As a result of the surface modification, affinity of the osteoblastic cells on the FEP surface increased, which was also confirmed by increase in the cell area. Finally, cell micro-patterning on the FEP surface was carried out based on difference in the affinity between modified and unmodified surfaces patterned by masking method. (author)

Polychromatic X-ray Micro- and Nano-Beam Science and Instrumentation

Science.gov (United States)

Ice, G. E.; Larson, B. C.; Liu, W.; Barabash, R. I.; Specht, E. D.; Pang, J. W. L.; Budai, J. D.; Tischler, J. Z.; Khounsary, A.; Liu, C.; Macrander, A. T.; Assoufid, L.

2007-01-01

Polychromatic x-ray micro- and nano-beam diffraction is an emerging nondestructive tool for the study of local crystalline structure and defect distributions. Both long-standing fundamental materials science issues, and technologically important questions about specific materials systems can be uniquely addressed. Spatial resolution is determined by the beam size at the sample and by a knife-edge technique called differential aperture microscopy that decodes the origin of scattering from along the penetrating x-ray beam. First-generation instrumentation on station 34-ID-E at the Advanced Photon Source (APS) allows for nondestructive automated recovery of the three-dimensional (3D) local crystal phase and orientation. Also recovered are the local elastic-strain and the dislocation tensor distributions. New instrumentation now under development will further extend the applications of polychromatic microdiffraction and will revolutionize materials characterization.

Polychromatic X-ray Micro- and Nano-Beam Science and Instrumentation

International Nuclear Information System (INIS)

Ice, G.E.; Larson, Ben C.; Liu, Wenjun; Barabash, Rozaliya; Specht, Eliot D; Pang, Judy; Budai, John D.; Tischler, Jonathan Zachary; Khounsary, Ali; Liu, Chian; Macrander, Albert T.; Assoufid, Lahsen

2007-01-01

Polychromatic x-ray micro- and nano-beam diffraction is an emerging nondestructive tool for the study of local crystalline structure and defect distributions. Both long-standing fundamental materials science issues, and technologically important questions about specific materials systems can be uniquely addressed. Spatial resolution is determined by the beam size at the sample and by a knife-edge technique called differential aperture microscopy that decodes the origin of scattering from along the penetrating x-ray beam. First-generation instrumentation on station 34-ID-E at the Advanced Photon Source (APS) allows for nondestructive automated recovery of the three-dimensional (3D) local crystal phase and orientation. Also recovered are the local elastic-strain and the dislocation tensor distributions. New instrumentation now under development will further extend the applications of polychromatic microdiffraction and will revolutionize materials characterization

Effect of Micro-Bubbles in Water on Beam Patterns of Parametric Array

Science.gov (United States)

Hashiba, Kunio; Masuzawa, Hiroshi

2003-05-01

The improvement in efficiency of a parametric array by nonlinear oscillation of micro-bubbles in water is studied in this paper. The micro-bubble oscillation can increase the nonlinear coefficient of the acoustic medium. The amplitude of the difference-frequency wave along the longitudinal axis and its beam patterns in the field including the layer with micro-bubbles were analyzed using a Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation. As a result, the largest improvement in efficiency was obtained and a narrow parametric beam was formed by forming a layer with micro-bubbles in front of a parametric sound radiator as thick as about the shock formation distance. If the layer becomes significantly thicker than the distance, the beam of the difference-frequency wave in the far-field will become broader. If the layer is significantly thinner than the distance, the intensity level of the wave in the far-field will be too low.

Micro-CT Arthrographic Analysis of Monosodium Iodoacetate- Induced Osteoarthritis in Rat Knees

International Nuclear Information System (INIS)

Kwon, Jong Won; Kang, Heung Sik; Hong, Sung Hwan

2010-01-01

To evaluate the arthrographic findings of MIA-induced osteoarthritis in rat knees using the micro-CT arthrography. Intra-articular monosodium iodoacetate (MIA) injection-induced arthritis was induced in the right knees of twelve rats; their left knees served as the control group. Eight weeks after MIA injection, micro-CT arthrography was performed on each knee. We measured the thickness of retro-patellar cartilages, the distances of tibio-femoral joint space, subchondral bone plate thickness, tibial epiphyseal height, and transverse patellar diameter. Subchondral trabecular bone indices were measured in the tibial lateral condylar epiphysis. The data were analyzed statistically using a paired t-test. The retro-patellar articular cartilage showed thinning on the right side that had been induced to develop osteoarthritis. The right knees showed a significant reduction in the distance of the tibio-femoral joint space, prominent patellar osteophytes, and the resorption of subchondral bone. Among the subchondral trabecular bone indices, percent bone volume, and trabecular thickness was reduced on the right side. The articular cartilage thickness of MIA-induced arthritis model could be measured using micro- CT arthrography. It was possible to evaluate the osteoarthritic findings including the change in subchondral bone plate thickness, osteophyte formation, and subchondral bone resorption, as well as quantitatively analyze the trabecular bone indices

Micro-CT Arthrographic Analysis of Monosodium Iodoacetate- Induced Osteoarthritis in Rat Knees

Energy Technology Data Exchange (ETDEWEB)

Kwon, Jong Won [Samsung Medical Center, Sungkyunkwan University, Seoul (Korea, Republic of); Kang, Heung Sik [Seoul National University Bundang Hospital, Seongnam (Korea, Republic of); Hong, Sung Hwan [Seoul National University College of Medicine, Seoul (Korea, Republic of)

2010-10-15

To evaluate the arthrographic findings of MIA-induced osteoarthritis in rat knees using the micro-CT arthrography. Intra-articular monosodium iodoacetate (MIA) injection-induced arthritis was induced in the right knees of twelve rats; their left knees served as the control group. Eight weeks after MIA injection, micro-CT arthrography was performed on each knee. We measured the thickness of retro-patellar cartilages, the distances of tibio-femoral joint space, subchondral bone plate thickness, tibial epiphyseal height, and transverse patellar diameter. Subchondral trabecular bone indices were measured in the tibial lateral condylar epiphysis. The data were analyzed statistically using a paired t-test. The retro-patellar articular cartilage showed thinning on the right side that had been induced to develop osteoarthritis. The right knees showed a significant reduction in the distance of the tibio-femoral joint space, prominent patellar osteophytes, and the resorption of subchondral bone. Among the subchondral trabecular bone indices, percent bone volume, and trabecular thickness was reduced on the right side. The articular cartilage thickness of MIA-induced arthritis model could be measured using micro- CT arthrography. It was possible to evaluate the osteoarthritic findings including the change in subchondral bone plate thickness, osteophyte formation, and subchondral bone resorption, as well as quantitatively analyze the trabecular bone indices.

Frequency Shifts of Micro and Nano Cantilever Beam Resonators Due to Added Masses

KAUST Repository

Bouchaala, Adam M.

2016-03-21

We present analytical and numerical techniques to accurately calculate the shifts in the natural frequencies of electrically actuated micro and nano (carbon nanotubes (CNTs)) cantilever beams implemented as resonant sensors for mass detection of biological entities, particularly Escherichia coli (E. coli) and prostate specific antigen (PSA) cells. The beams are modeled as Euler-Bernoulli beams, including the nonlinear electrostatic forces and the added biological cells, which are modeled as discrete point masses. The frequency shifts due to the added masses of the cells are calculated for the fundamental and higher-order modes of vibrations. Analytical expressions of the natural frequency shifts under a direct current (DC) voltage and an added mass have been developed using perturbation techniques and the Galerkin approximation. Numerical techniques are also used to calculate the frequency shifts and compared with the analytical technique. We found that a hybrid approach that relies on the analytical perturbation expression and the Galerkin procedure for calculating accurately the static behavior presents the most computationally efficient approach. We found that using higher-order modes of vibration of micro-electro-mechanical-system (MEMS) beams or miniaturizing the sizes of the beams to nanoscale leads to significant improved frequency shifts, and thus increased sensitivities. © 2016 by ASME.

Micro-patterns fabrication using focused proton beam lithography

Czech Academy of Sciences Publication Activity Database

Cutroneo, Mariapompea; Havránek, Vladimír; Macková, Anna; Semián, Vladimír; Torrisi, L.; Calcagno, L.

2016-01-01

Roč. 371, MAR (2016), s. 344-349 ISSN 0168-583X. [22nd International conference on Ion Beam Analysis (IBA). Opatija, 14.06.2015-19.06.2015] R&D Projects: GA MŠk(CZ) LM2011019; GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:61389005 Keywords : ion-micro-beam * STIM analysis * pattern in PMMA Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.109, year: 2016

TU-H-207A-03: CT Hounsfield Unit Accuracy: Effect of Beam Hardening On Phantom and Clinical Whole-Body CT Images

Energy Technology Data Exchange (ETDEWEB)

Ai, H; Wendt, R [The University of Texas MD Anderson Cancer Center, Houston, TX (United States)

2016-06-15

Purpose: To assess the effect of beam hardening on measured CT HU values. Methods: An anthropomorphic knee phantom was scanned with the CT component of a GE Discovery 690 PET/CT scanner (120kVp, 300mAs, 40?0.625mm collimation, pitch=0.984, FOV=500mm, matrix=512?512) with four different scan setups, each of which induces different degrees of beam hardening by introducing additional attenuation media into the field of view. Homogeneous voxels representing “soft tissue” and “bone” were segmented by HU thresholding followed by a 3D morphological erosion operation which removes the non-homogenous voxels located on the interface of thresholded tissue mask. HU values of segmented “soft tissue” and “bone” were compared.Additionally, whole-body CT data with coverage from the skull apex to the end of toes were retrospectively retrieved from seven PET/CT exams to evaluate the effect of beam hardening in vivo. Homogeneous bone voxels were segmented with the same method previously described. Total In-Slice Attenuation (TISA) for each CT slice, defined as the summation of HU values over all voxels within a CT slice, was calculated for all slices of the seven whole-body CT datasets and evaluated against the mean HU values of homogeneous bone voxels within that slice. Results: HU values measured from the phantom showed that while “soft tissue” HU values were unaffected, added attenuation within the FOV caused noticeable decreases in the measured HU values of “bone” voxels. A linear relationship was observed between bone HU and TISA for slices of the torso and legs, but not of the skull. Conclusion: Beam hardening effect is not an issue of concern for voxels with HU in the soft tissue range, but should not be neglected for bone voxels. A linear relationship exists between bone HU and the associated TISA in non-skull CT slices, which can be exploited to develop a correction strategy.

Relationships between cone beam CT value and physical density in image guided radiation therapy

International Nuclear Information System (INIS)

Jiang Xiaoqin; Bai Sen; Zhong Renming; Tang Zhiquan; Jiang Qinfeng; Li Tao

2007-01-01

Objective: To evaluate the main factors affecting the relationship between physical density and CT value in cone-beam computed tomography(CBCT) for imaging guided radiation therapy(IGRT) by comparing the CT value in the image from cone-beam scanner and from fan-beam (FBCT) scanner of a reference phantom. Methods: A taking-park reference phantom with a set of tissue equivalent inserts was scanned at different energies different fields of view (FOV) for IGRT-CBCT and FBCT. The CT value of every insert was measured and compared. Results: The position of inserts in phantom, the size of phantom, the FOV of scanner and different energies had more effect on the relationships between physical density and the CT value from IGRT-CBCT than those from the normal FBCT. The higher the energy was, the less effect of the position of inserts in phantom, the size of phantom and the FOV of scanner on CT value, and the poorer density contrast was observed. Conclusion: At present, the CT value of IGRT-CBCT is not in the true HU value since the manufacturer has not corrected its number. Therefore, we are not able to use the CT value of CBCT for dose calculation in TPS. (authors)

Micro-CT analyses of historical bone samples presenting with osteomyelitis

Energy Technology Data Exchange (ETDEWEB)

Lamm, C.; Pietschmann, P. [Medical University Vienna (MUV), Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Vienna (Austria); Dockner, M.; Weber, G.W. [University of Vienna, Department of Anthropology, Vienna (Austria); University of Vienna, Core Facility for Micro-Computed Tomography, Vienna (Austria); Pospischek, B.; Winter, E.; Patzak, B. [Museum of Natural History (NHM), Collection of Anatomical Pathology in the Madhouse Tower, Vienna (Austria); Pretterklieber, M. [Medical University of Vienna (MUV), Department of Applied Anatomy, Vienna (Austria)

2015-10-15

Osteomyelitis is an inflammation of the bone marrow mainly caused by bacteria such as Staphylococcus aureus. It typically affects long bones, e.g. femora, tibiae and humeri. Recently micro-computed tomography (μCT) techniques offer the opportunity to investigate bone micro-architecture in great detail. Since there is no information on long bone microstructure in osteomyelitis, we studied historic bone samples with osteomyelitis by μCT. We investigated 23 femora of 22 individuals suffering from osteomyelitis provided by the Collection of Anatomical Pathology, Museum of Natural History, Vienna (average age 44 ±19 years); 9 femora from body donors made available by the Department of Applied Anatomy, Medical University of Vienna (age range, 56-102 years) were studied as controls. Bone microstructure was assessed by μCT VISCOM X 8060 II with a minimal resolution of 18 μm. In the osteomyelitic femora, most prominent alterations were seen in the cortical compartment. In 71.4 % of the individuals with osteomyelitis, cortical porosity occurred. 57.1 % of the individuals showed cortical thinning. In 42.9 % trabecularisation of cortical bone was observed. Osteomyelitis is associated with severe alterations of cortical bone structure otherwise typically observed at old age such as cortical porosity and cortical thinning. (orig.)

Assessment of protocols in cone beam CT with symmetric and asymmetric beam using effective dose and Pka

International Nuclear Information System (INIS)

Batista, W. O.; Linhares de O, M. V.; Soares, M. R.; Maia, A. F.; Caldas, L. V. E.

2014-08-01

The cone beam CT is an emerging technology in dental radiology with significant differences the point of view of design technology between the various manufacturers on the world market. This study aims to evaluate and compare protocols with similar purposes in a cone beam CT scanner using TLDs and air kerma - area product (P ka ) as kerma index. Measurements were performed on two protocols used to obtain the image the maxilla-mandible in equipment Gendex GXCB 500: Protocol [GX1] extended diameter and asymmetric beam (14 cm x 8.5 cm - maxilla / mandible) and protocol [GX2] symmetrical beam (8.5 cm x 8.5 cm - maxillary / mandible). Was used LiF dosimeters (TLD 100) inserted into a female anthropomorphic phantom manufactured by Radiology Support Devices. For all protocols evaluated the value of P ka using a meter Diamentor E2 and PTW system Radcal Rapidose. The results obtained for Effective Dose / P ka these measurements were separated by protocol image. Protocol [GX1]: 44.5 μSv/478 mGy cm 2 ; protocol [GX2]: 54.8 μSv/507 mGy cm 2 . These values indicate that the relationship between the diameter of the image acquired in the protocol [GX1] and the diameter of the image in the protocol [GX2] is equal to 1.65, the Effective Dose for the first protocol has lower value at 18%. P ka values reveal very similar results between the two protocols, although, common sense leads to the interpretation that imaging protocols with field of view (Fov) of large diameters imply high values of effective dose when compared to small diameters. However, in this particular case, this is not true due to the asymmetrical beam technology. Conclude that for the cases where the scanner uses asymmetric beam to obtain images with large diameters that cover the entire face there are advantages from the point of view of reducing the exposure of patients with respect to the use of symmetrical beam and / or to Fov images with a smaller diameter. (Author)

DESIGN of MICRO CANTILEVER BEAM for VAPOUR DETECTION USING COMSOL MULTI PHYSICS SOFTWARE

OpenAIRE

Sivacoumar R; Parvathy JM; Pratishtha Deep

2015-01-01

This paper gives an overview of micro cantilever beam of various shapes and materials for vapour detection. The design of micro cantilever beam, analysis and simulation is done for each shape. The simulation is done using COMSOL Multi physics software using structural mechanics and chemical module. The simulation results of applied force and resulting Eigen frequencies will be analyzed for different beam structures. The vapour analysis is done using flow cell that consists of chemical pill...

A comparison of micro-CT, microradiography and histomorphometry in bone research

NARCIS (Netherlands)

Gielkens, Pepijn F. M.; Schortinghuis, Jurjen; de Jong, Johan R.; Huysmans, Marie Charlotte D. N. J. M.; van Leeuwen, M. Barbara M.; Raghoebar, Gerry M.; Bos, Ruud R. M.; Stegenga, Boudewijn

Objective: Intraobserver reliability and agreement were determined for microradiography (MR), micro-computed tomography (mu CT) and histomorphometry (HM). These three modalities were compared for quantitative measurements of bone formation and graft modelling in rat mandibular defects and grafts.

Integrated visualization of multi-angle bioluminescence imaging and micro CT

NARCIS (Netherlands)

Kok, P.; Dijkstra, J.; Botha, C.P.; Post, F.H.; Kaijzel, E.; Que, I.; Löwik, C.W.G.M.; Reiber, J.H.C.; Lelieveldt, B.P.F.

2007-01-01

This paper explores new methods to visualize and fuse multi-2D bioluminescence imaging (BLI) data with structural imaging modalities such as micro CT and MR. A geometric, back-projection-based 3D reconstruction for superficial lesions from multi-2D BLI data is presented, enabling a coarse estimate

A limited cone-beam CT for dental, head and neck regions

International Nuclear Information System (INIS)

Kirimura, Susumu

2004-01-01

Recently, limited cone-beam CTs for dental or head-and-neck regions, which utilize two-dimensional X-ray detectors, have been gaining popularity. With one single rotation, they provide high-resolution volumetric data of a small region, which is suitable for specialized medical applications in the dental and otorhinolaryngology fields. It is particularly useful in visualizing small structures such as temporal, maxilla or mandibula bones. Since the imaging area is limited to a small but sufficient region, it can reduce unnecessary X-ray exposure to the patient. As the entire system is designed to be space-efficient compared to existing CT systems in the field, it is possible fit the unit into a small clinic. This type of device can be a far more practical and useful tool than an existing CT for special applications requiring detailed imaging of the fine bone structures of teeth, the middle ear, etc. (author)

Polymer Assembly Encapsulation of Lanthanide Nanoparticles as Contrast Agents for In Vivo Micro-CT.

Science.gov (United States)

Cruje, Charmainne; Dunmore-Buyze, Joy; MacDonald, Jarret P; Holdsworth, David W; Drangova, Maria; Gillies, Elizabeth R

2018-03-12

Despite recent technological advancements in microcomputed tomography (micro-CT) and contrast agent development, preclinical contrast agents are still predominantly iodine-based. Higher contrast can be achieved when using elements with higher atomic numbers, such as lanthanides; lanthanides also have X-ray attenuation properties that are ideal for spectral CT. However, the formulation of lanthanide-based contrast agents at the high concentrations required for vascular imaging presents a significant challenge. In this work, we developed an erbium-based contrast agent that meets micro-CT imaging requirements, which include colloidal stability upon redispersion at high concentrations, evasion of rapid renal clearance, and circulation times of tens of minutes in small animals. Through systematic studies with poly(ethylene glycol) (PEG)-poly(propylene glycol), PEG-polycaprolactone, and PEG-poly(l-lactide) (PLA) block copolymers, the amphiphilic block copolymer PEG 114 -PLA 53 was identified to be ideal for encapsulating oleate-coated lanthanide-based nanoparticles for in vivo intravenous administration. We were able to synthesize a contrast agent containing 100 mg/mL of erbium that could be redispersed into colloidally stable particles in saline after lyophilization. Contrast enhancement of over 250 HU was achieved in the blood pool for up to an hour, thereby meeting the requirements of live animal micro-CT.

Evaluation of Biomaterials Using Micro-Computerized Tomography

International Nuclear Information System (INIS)

Torris, A. T. Arun; Columbus, K. C. Soumya; Saaj, U. S.; Krishnan, Kalliyana V.; Nair, Manitha B.

2008-01-01

Micro-computed tomography or Micro-CT is a high resolution, non-invasive, x-ray scanning technique that allows precise three-dimensional imaging and quantification of micro-architectural and structural parameters of objects. Tomographic reconstruction is based on a cone-beam convolution-back-projection algorithm. Micro-architectural and structural parameters such as porosity, surface area to volume ratio, interconnectivity, pore size, wall thickness, anisotropy and cross-section area of biomaterials and bio-specimens such as trabecular bone, polymer scaffold, bio-ceramics and dental restorative were evaluated through imaging and computer aided manipulation of the object scan data sets.

Micro-CT features of intermediate gunshot wounds severely damaged by fire.

Science.gov (United States)

Fais, Paolo; Giraudo, Chiara; Boscolo-Berto, Rafael; Amagliani, Alessandro; Miotto, Diego; Feltrin, Giampietro; Viel, Guido; Ferrara, S Davide; Cecchetto, Giovanni

2013-03-01

Incineration or extensive burning of the body, causing changes in the content and distribution of fluids, fixation and shrinking processes of tissues, can alter the typical macroscopic and microscopic characteristics of firearm wounds, hampering or at least complicating the reconstruction of gunshot fatalities. The present study aims at evaluating the potential role of micro-computed tomography (micro-CT) for detecting and quantifying gunshot residue (GSR) particles in experimentally produced intermediate-range gunshot wounds severely damaged by fire. Eighteen experimental shootings were performed on 18 sections of human calves surgically amputated for medical reasons at three different firing distances (5, 15 and 30 cm). Six stab wounds produced with an ice pick were used as controls. Each calf section underwent a charring cycle, being placed in a wood-burning stove for 4 min at a temperature of 400 °C. At visual inspection, the charred entrance wounds could not be differentiated from the exit lesions and the stab wounds. On the contrary, micro-CT analysis showed the presence of GSR particles in all burnt entrance gunshot wounds, while GSR was absent in the exit and stab wounds. The GSR deposits of the firearm lesions inflicted at very close distance (5 cm) were mainly constituted of huge particles (diameter >150 μm) with an irregular shape and well-delineated edges; at greater distances (15 and 30 cm), agglomerates of tiny radiopaque particles scattered in the epidermis and dermis layers were evident. Statistical analysis demonstrated that also in charred firearm wounds the amount of GSR roughly correlates with the distance from which the gun was fired. The obtained results suggest that micro-CT analysis can be a valid screening tool for identifying entrance gunshot wounds and for differentiating firearm wounds from sharp-force injuries in bodies severely damaged by fire.

Combined Fluoroscopy- and CT-Guided Transthoracic Needle Biopsy Using a C-Arm Cone-Beam CT System: Comparison with Fluoroscopy-Guided Biopsy

Energy Technology Data Exchange (ETDEWEB)

Cheung, Joo Yeon; Kim, Yoo Kyung; Shim, Sung Shine; Lim, Soo Mee [School of Medicine, Ewha Womans University, Seoul (Korea, Republic of)

2011-02-15

The aim of this study was to evaluate the usefulness of combined fluoroscopy- and CT-guided transthoracic needle biopsy (FC-TNB) using a cone beam CT system in comparison to fluoroscopy-guided TNB (F-TNB). We retrospectively evaluated 74 FC-TNB cases (group A) and 97 F-TNB cases (group B) to compare their respective diagnostic accuracies according to the size and depth of the lesion, as well as complications, procedure time, and radiation dose. The sensitivity for malignancy and diagnostic accuracy for small (< 30 mm in size) and deep ({>=} 50 mm in depth) lesions were higher in group A (91% and 94%, 92% and 94%) than in group B (73% and 81%, 84% and 88%), however not statistically significant (p > 0.05). Concerning lesions {>=} 30 mm in size and < 50 mm in depth, both groups displayed similar results (group A, 91% and 92%, 80% and 87%: group B, 90% and 92%, 86% and 90%). Pneumothorax occurred 26% of the time in group A and 14% for group B. The mean procedure time and patient skin dose were significantly higher in group A (13.6 {+-} 4.0 minutes, 157.1 {+-} 76.5 mGy) than in group B (9.0 {+-} 3.5 minutes, 21.9 {+-} 15.2 mGy) (p < 0.05). Combined fluoroscopy- and CT-guided TNB allows the biopsy of small (< 30 mm) and deep lesions ({>=} 50 mm) with high diagnostic accuracy and short procedure times, whereas F-TNB is still a useful method for large and superficial lesions with a low radiation dose

Motion tolerant iterative reconstruction algorithm for cone-beam helical CT imaging

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Hisashi; Goto, Taiga; Hirokawa, Koichi; Miyazaki, Osamu [Hitachi Medical Corporation, Chiba-ken (Japan). CT System Div.

2011-07-01

We have developed a new advanced iterative reconstruction algorithm for cone-beam helical CT. The features of this algorithm are: (a) it uses separable paraboloidal surrogate (SPS) technique as a foundation for reconstruction to reduce noise and cone-beam artifact, (b) it uses a view weight in the back-projection process to reduce motion artifact. To confirm the improvement of our proposed algorithm over other existing algorithm, such as Feldkamp-Davis-Kress (FDK) or SPS algorithm, we compared the motion artifact reduction, image noise reduction (standard deviation of CT number), and cone-beam artifact reduction on simulated and clinical data set. Our results demonstrate that the proposed algorithm dramatically reduces motion artifacts compared with the SPS algorithm, and decreases image noise compared with the FDK algorithm. In addition, the proposed algorithm potentially improves time resolution of iterative reconstruction. (orig.)

Optimization of a retrospective technique for respiratory-gated high speed micro-CT of free-breathing rodents

International Nuclear Information System (INIS)

Ford, Nancy L; Wheatley, Andrew R; Holdsworth, David W; Drangova, Maria

2007-01-01

The objective of this study was to develop a technique for dynamic respiratory imaging using retrospectively gated high-speed micro-CT imaging of free-breathing mice. Free-breathing C57Bl6 mice were scanned using a dynamic micro-CT scanner, comprising a flat-panel detector mounted on a slip-ring gantry. Projection images were acquired over ten complete gantry rotations in 50 s, while monitoring the respiratory motion in synchrony with projection-image acquisition. Projection images belonging to a selected respiratory phase were retrospectively identified and used for 3D reconstruction. The effect of using fewer gantry rotations-which influences both image quality and the ability to quantify respiratory function-was evaluated. Images reconstructed using unique projections from six or more gantry rotations produced acceptable images for quantitative analysis of lung volume, CT density, functional residual capacity and tidal volume. The functional residual capacity (0.15 ± 0.03 mL) and tidal volumes (0.08 ± 0.03 mL) measured in this study agree with previously reported measurements made using prospectively gated micro-CT and at higher resolution (150 μm versus 90 μm voxel spacing). Retrospectively gated micro-CT imaging of free-breathing mice enables quantitative dynamic measurement of morphological and functional parameters in the mouse models of respiratory disease, with scan times as short as 30 s, based on the acquisition of projection images over six gantry rotations

Optimization of a retrospective technique for respiratory-gated high speed micro-CT of free-breathing rodents

Energy Technology Data Exchange (ETDEWEB)

Ford, Nancy L [Department of Physics, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Wheatley, Andrew R [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada); Holdsworth, David W [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada); Drangova, Maria [Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, PO Box 5015, London, Ontario N6A 5K8 (Canada)

2007-09-21

The objective of this study was to develop a technique for dynamic respiratory imaging using retrospectively gated high-speed micro-CT imaging of free-breathing mice. Free-breathing C57Bl6 mice were scanned using a dynamic micro-CT scanner, comprising a flat-panel detector mounted on a slip-ring gantry. Projection images were acquired over ten complete gantry rotations in 50 s, while monitoring the respiratory motion in synchrony with projection-image acquisition. Projection images belonging to a selected respiratory phase were retrospectively identified and used for 3D reconstruction. The effect of using fewer gantry rotations-which influences both image quality and the ability to quantify respiratory function-was evaluated. Images reconstructed using unique projections from six or more gantry rotations produced acceptable images for quantitative analysis of lung volume, CT density, functional residual capacity and tidal volume. The functional residual capacity (0.15 {+-} 0.03 mL) and tidal volumes (0.08 {+-} 0.03 mL) measured in this study agree with previously reported measurements made using prospectively gated micro-CT and at higher resolution (150 {mu}m versus 90 {mu}m voxel spacing). Retrospectively gated micro-CT imaging of free-breathing mice enables quantitative dynamic measurement of morphological and functional parameters in the mouse models of respiratory disease, with scan times as short as 30 s, based on the acquisition of projection images over six gantry rotations.

From the sample preparation to the volume rendering images of small animals: A step by step example of a procedure to carry out the micro-CT study of the leafhopper insect Homalodisca vitripennis (Hemiptera: Cicadellidae)

Science.gov (United States)

Advances in micro-CT, digital computed tomography (CT) scan uses X-rays to make detailed pictures of structures inside of the body. Combining micro-CT with Digital Video Library systems, and linking this to Big Data, will change the way researchers, entomologist, and the public search and use anato...

Three-rooted premolar analyzed by high-resolution and cone beam CT.

Science.gov (United States)

Marca, Caroline; Dummer, Paul M H; Bryant, Susan; Vier-Pelisser, Fabiana Vieira; Só, Marcus Vinicius Reis; Fontanella, Vania; Dutra, Vinicius D'avila; de Figueiredo, José Antonio Poli

2013-07-01

The aim of this study was to analyze the variations in canal and root cross-sectional area in three-rooted maxillary premolars between high-resolution computed tomography (μCT) and cone beam computed tomography (CBCT). Sixteen extracted maxillary premolars with three distinct roots and fully formed apices were scanned using μCT and CBCT. Photoshop CS software was used to measure root and canal cross-sectional areas at the most cervical and the most apical points of each root third in images obtained using the two tomographic computed (CT) techniques, and at 30 root sections equidistant from both root ends using μCT images. Canal and root areas were compared between each method using the Student t test for paired samples and 95 % confidence intervals. Images using μCT were sharper than those obtained using CBCT. There were statistically significant differences in mean area measurements of roots and canals between the μCT and CBCT techniques (P < 0.05). Root and canal areas had similar variations in cross-sectional μCT images and became proportionally smaller in a cervical to apical direction as the cementodentinal junction was approached, from where the area then increased apically. Although variation was similar in the roots and canals under study, CBCT produced poorer image details than μCT. Although CBCT is a strong diagnosis tool, it still needs improvement to provide accuracy in details of the root canal system, especially in cases with anatomical variations, such as the three-rooted maxillary premolars.

New lens system using toroidal magnetic field for intense ion beam

International Nuclear Information System (INIS)

Mohri, Akihiro; Ikuta, Kazunari; Fujita, Junji.

1976-11-01

The use of toroidal magnetic field as a lens system is proposed for producing intense ion beam. The characteristics of the lens system are obtained both analytically and numerically. Some examples of ray-trajectories are presented for different focal lengths. The system is applicable to neutral beam injection heating and micro-pellet implosion for nuclear fusion, and to the other fields such as ion beam X-ray lasers. (auth.)

SU-F-J-205: Effect of Cone Beam Factor On Cone Beam CT Number Accuracy

Energy Technology Data Exchange (ETDEWEB)

Yao, W; Hua, C; Farr, J; Brady, S; Merchant, T [St. Jude Children’s Research Hospital, Memphis, TN (United States)

2016-06-15

Purpose: To examine the suitability of a Catphan™ 700 phantom for image quality QA of a cone beam computed tomography (CBCT) system deployed for proton therapy. Methods: Catphan phantoms, particularly Catphan™ 504, are commonly used in image quality QA for CBCT. As a newer product, Catphan™ 700 offers more tissue equivalent inserts which may be useful for generating the electron density – CT number curve for CBCT based treatment planning. The sensitometry-and-geometry module used in Catphan™ 700 is located at the end of the phantom and after the resolution line pair module. In Catphan™ 504 the line pair module is located at the end of the phantom and after the sensitometry-and-geometry module. To investigate the effect of difference in location on CT number accuracy due to the cone beam factor, we scanned the Catphan™ 700 with the central plane of CBCT at the center of the phantom, line pair and sensitometry-andgeometry modules of the phantom, respectively. The protocol head and thorax scan modes were used. For each position, scans were repeated 4 times. Results: For the head scan mode, the standard deviation (SD) of the CT numbers of each insert under 4 repeated scans was up to 20 HU, 11 HU, and 11 HU, respectively, for the central plane of CBCT located at the center of the phantom, line pair, and sensitometry-and-geometry modules of the phantom. The mean of the SD was 9.9 HU, 5.7 HU, and 5.9 HU, respectively. For the thorax mode, the mean of the SD was 4.5 HU, 4.4 HU, and 4.4 HU, respectively. The assessment of image quality based on resolution and spatial linearity was not affected by imaging location changes. Conclusion: When the Catphan™ 700 was aligned to the center of imaging region, the CT number accuracy test may not meet expectations. We recommend reconfiguration of the modules.

Synchrotron microCT imaging of soft tissue in juvenile zebrafish reveals retinotectal projections

Science.gov (United States)

Xin, Xuying; Clark, Darin; Ang, Khai Chung; van Rossum, Damian B.; Copper, Jean; Xiao, Xianghui; La Riviere, Patrick J.; Cheng, Keith C.

2017-02-01

Biomedical research and clinical diagnosis would benefit greatly from full volume determinations of anatomical phenotype. Comprehensive tools for morphological phenotyping are central for the emerging field of phenomics, which requires high-throughput, systematic, accurate, and reproducible data collection from organisms affected by genetic, disease, or environmental variables. Theoretically, complete anatomical phenotyping requires the assessment of every cell type in the whole organism, but this ideal is presently untenable due to the lack of an unbiased 3D imaging method that allows histopathological assessment of any cell type despite optical opacity. Histopathology, the current clinical standard for diagnostic phenotyping, involves the microscopic study of tissue sections to assess qualitative aspects of tissue architecture, disease mechanisms, and physiological state. However, quantitative features of tissue architecture such as cellular composition and cell counting in tissue volumes can only be approximated due to characteristics of tissue sectioning, including incomplete sampling and the constraints of 2D imaging of 5 micron thick tissue slabs. We have used a small, vertebrate organism, the zebrafish, to test the potential of microCT for systematic macroscopic and microscopic morphological phenotyping. While cell resolution is routinely achieved using methods such as light sheet fluorescence microscopy and optical tomography, these methods do not provide the pancellular perspective characteristic of histology, and are constrained by the limited penetration of visible light through pigmented and opaque specimens, as characterizes zebrafish juveniles. Here, we provide an example of neuroanatomy that can be studied by microCT of stained soft tissue at 1.43 micron isotropic voxel resolution. We conclude that synchrotron microCT is a form of 3D imaging that may potentially be adopted towards more reproducible, large-scale, morphological phenotyping of optically

Geometrical E-beam proximity correction for raster scan systems

Science.gov (United States)

Belic, Nikola; Eisenmann, Hans; Hartmann, Hans; Waas, Thomas

1999-04-01

High pattern fidelity is a basic requirement for the generation of masks containing sub micro structures and for direct writing. Increasing needs mainly emerging from OPC at mask level and x-ray lithography require a correction of the e-beam proximity effect. The most part of e-beam writers are raster scan system. This paper describes a new method for geometrical pattern correction in order to provide a correction solution for e-beam system that are not able to apply variable doses.

Study of CT Scan Flooding System at High Temperature and Pressure

Science.gov (United States)

Chen, X. Y.

2017-12-01

CT scan flooding experiment can scan micro-pore in different flooding stages by the use of CT scan technology, without changing the external morphology and internal structure of the core, and observe the distribution characterization in pore medium of different flooding fluid under different pressure.thus,it can rebuilt the distribution images of oil-water distribution in different flooding stages. However,under extreme high pressure and temperature conditions,the CT scan system can not meet the requirements. Container of low density materials or thin shell can not resist high pressure,while high density materials or thick shell will cause attenuation and scattering of X-ray. The experiment uses a simple Ct scanning systems.X ray from a point light source passing trough a micro beryllium shell on High pressure stainless steal container,continuously irradiates the core holder that can continuously 360° rotate along the core axis. A rare earth intensifying screen behind the core holder emitting light when irradiated with X ray can show the core X ray section image. An optical camera record the core X ray images through a transparency high pressure glazing that placed on the High pressure stainless steal container.Thus,multiple core X ray section images can reconstruct the 3D core reconstruction after a series of data processing.The experiment shows that both the micro beryllium shell and rare earth intensifying screen can work in high temperature and high pressure environment in the stainless steal container. This way that X-ray passes through a thin layer of micro beryllium shell , not high pressure stainless steal shell,avoid the attenuation and scattering of X-ray from the container shell,while improving the high-pressure experiment requirements.

A new method for x-ray scatter correction: first assessment on a cone-beam CT experimental setup

International Nuclear Information System (INIS)

Rinkel, J; Gerfault, L; Esteve, F; Dinten, J-M

2007-01-01

Cone-beam computed tomography (CBCT) enables three-dimensional imaging with isotropic resolution and a shorter acquisition time compared to a helical CT scanner. Because a larger object volume is exposed for each projection, scatter levels are much higher than in collimated fan-beam systems, resulting in cupping artifacts, streaks and quantification inaccuracies. In this paper, a general method to correct for scatter in CBCT, without supplementary on-line acquisition, is presented. This method is based on scatter calibration through off-line acquisition combined with on-line analytical transformation based on physical equations, to adapt calibration to the object observed. The method was tested on a PMMA phantom and on an anthropomorphic thorax phantom. The results were validated by comparison to simulation for the PMMA phantom and by comparison to scans obtained on a commercial multi-slice CT scanner for the thorax phantom. Finally, the improvements achieved with the new method were compared to those obtained using a standard beam-stop method. The new method provided results that closely agreed with the simulation and with the conventional CT scanner, eliminating cupping artifacts and significantly improving quantification. Compared to the beam-stop method, lower x-ray doses and shorter acquisition times were needed, both divided by a factor of 9 for the same scatter estimation accuracy

Phenotypic characterization of skeletal abnormalities of osteopotentia mutant mice by micro-CT: a descriptive approach with emphasis on reconstruction techniques

Energy Technology Data Exchange (ETDEWEB)

Roemer, Frank W. [Department of Radiology, Klinikum Augsburg, Augsburg (Germany); Boston University School of Medicine, Quantitative Imaging Center, Boston, MA (United States); University of California, San Francisco, Osteoporosis and Arthritis Research Group, San Francisco, CA (United States); Boston University Medical Center, Department of Radiology, Boston, MA (United States); Mohr, Andreas [University of California, San Francisco, Osteoporosis and Arthritis Research Group, San Francisco, CA (United States); Sligo General Hospital, Department of Radiology, Sligo (Ireland); Guermazi, Ali [Boston University School of Medicine, Quantitative Imaging Center, Boston, MA (United States); University of California, San Francisco, Osteoporosis and Arthritis Research Group, San Francisco, CA (United States); Jiang, Yebin [University of California, San Francisco, Osteoporosis and Arthritis Research Group, San Francisco, CA (United States); University of Michigan Medical School, Osteoporosis and Arthritis Laboratory, Musculoskeletal Division, Department of Radiology, Ann Arbor, MI (United States); Schlechtweg, Philipp [University of Erlangen, Department of Radiology, Erlangen (Germany); Genant, Harry K. [University of California, San Francisco, Osteoporosis and Arthritis Research Group, San Francisco, CA (United States); CCBR-SYNARC, Inc., San Francisco, CA (United States); Sohaskey, Michael L. [University of California, Berkeley, Department of Molecular and Cell Biology and Center for Integrative Genomics, Berkeley, CA (United States)

2011-08-15

The novel protein osteopotentia (Opt) has recently been described as an essential regulator of postnatal osteoblast maturation and might possibly be responsible for some of the rarer types of osteogenesis imperfecta. Our aim was the evaluation of micro CT for the qualitative morphological assessment of skeletal abnormalities of Osteopotentia-mutant mice in comparison to radiography and histology. Four homozygous mice with insertional mutations in the Opt gene and three wild-type controls were examined ex vivo using radiography and micro-CT. Two of the homozygous animals were evaluated histologically (trichrome reagent). For the micro-CT evaluation three-dimensional (3D) surface reconstructions and two-dimensional (2D) multiplanar reformations (MPRs) were applied. The Opt-homozygous mice exhibited severe growth. The radiographic examinations showed osteopenia and fractures with hypertrophic callus formation and pseudarthroses of the forelimbs and ribs. Micro-CT confirmed these findings and was able to demonstrate additional fractures especially at smaller bones such as the metacarpals and phalanges. Additional characterization and superior delineation of cortices and fracture fragments was achieved by 2D MPRs. Histological correlation verified several of these imaging findings. Micro-CT is able to screen Opt-mutant mice for osseous pathologies and furthermore characterize these anomalies. The modality seems superior to conventional radiography, but is not able to demonstrate cellular pathology. However, histology is destructive and more time- and material-consuming than micro-CT. Additional information may be gathered by 2D MPRs. (orig.)

Phenotypic characterization of skeletal abnormalities of osteopotentia mutant mice by micro-CT: a descriptive approach with emphasis on reconstruction techniques

International Nuclear Information System (INIS)

Roemer, Frank W.; Mohr, Andreas; Guermazi, Ali; Jiang, Yebin; Schlechtweg, Philipp; Genant, Harry K.; Sohaskey, Michael L.

2011-01-01

The novel protein osteopotentia (Opt) has recently been described as an essential regulator of postnatal osteoblast maturation and might possibly be responsible for some of the rarer types of osteogenesis imperfecta. Our aim was the evaluation of micro CT for the qualitative morphological assessment of skeletal abnormalities of Osteopotentia-mutant mice in comparison to radiography and histology. Four homozygous mice with insertional mutations in the Opt gene and three wild-type controls were examined ex vivo using radiography and micro-CT. Two of the homozygous animals were evaluated histologically (trichrome reagent). For the micro-CT evaluation three-dimensional (3D) surface reconstructions and two-dimensional (2D) multiplanar reformations (MPRs) were applied. The Opt-homozygous mice exhibited severe growth. The radiographic examinations showed osteopenia and fractures with hypertrophic callus formation and pseudarthroses of the forelimbs and ribs. Micro-CT confirmed these findings and was able to demonstrate additional fractures especially at smaller bones such as the metacarpals and phalanges. Additional characterization and superior delineation of cortices and fracture fragments was achieved by 2D MPRs. Histological correlation verified several of these imaging findings. Micro-CT is able to screen Opt-mutant mice for osseous pathologies and furthermore characterize these anomalies. The modality seems superior to conventional radiography, but is not able to demonstrate cellular pathology. However, histology is destructive and more time- and material-consuming than micro-CT. Additional information may be gathered by 2D MPRs. (orig.)

EXD HME MicroCT Data Acquisition, Processing and Data Request Overview

Energy Technology Data Exchange (ETDEWEB)

Seetho, Isaac M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brown, William D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martz, Jr., Harry E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-12-06

This document is a short summary of the steps required for MicroCT evaluation of a specimen. This includes data acquisition through image analysis, for the EXD HME program. Expected outputs for each stage are provided. Data shall be shipped to LLNL as described herein.

Poster — Thur Eve — 06: Dose assessment of cone beam CT imaging protocols as part of SPECT/CT examinations

Energy Technology Data Exchange (ETDEWEB)

Tonkopi, E; Ross, AA [Department of Diagnostic Imaging, Queen Elizabeth II Health Sciences Centre, CDHA (Canada); Department of Radiology, Dalhousie University (Canada)

2014-08-15

Purpose: To assess radiation dose from the cone beam CT (CBCT) component of SPECT/CT studies and to compare with other CT examinations performed in our institution. Methods: We used an anthropomorphic chest phantom and the 6 cc ion chamber to measure entrance breast dose for several CBCT and diagnostic CT acquisition protocols. The CBCT effective dose was calculated with ImPACT software; the CT effective dose was evaluated from the DLP value and conversion factor, dependent on the anatomic region. The RADAR medical procedure radiation dose calculator was used to assess the nuclear medicine component of exam dose. Results: The entrance dose to the breast measured with the anthropomorphic phantom was 0.48 mGy and 9.41 mGy for cardiac and chest CBCT scans; and 4.59 mGy for diagnostic thoracic CT. The effective doses were 0.2 mSv, 3.2 mSv and 2.8 mSv respectively. For a small patient represented by the anthropomorphic phantom, the dose from the diagnostic CT was lower than from the CBCT scan, as a result of the exposure reduction options available on modern CT scanners. The CBCT protocols used the same fixed scanning techniques. The diagnostic CT dose based on the patient data was 35% higher than the phantom dose. For most SPECT/CT studies the dose from the CBCT component was comparable with the dose from the radiopharmaceutical. Conclusions: The patient radiation dose from the cone beam CT scan can be higher than that from a diagnostic CT and should be taken into consideration in evaluating total SPECT/CT patient dose.

Quantifying shape changes of silicone breast implants in a murine model using in vivo micro-CT.

Science.gov (United States)

Anderson, Emily E; Perilli, Egon; Carati, Colin J; Reynolds, Karen J

2017-08-01

A major complication of silicone breast implants is the formation of a capsule around the implant known as capsular contracture which results in the distortion of the implant. Recently, a mouse model for studying capsular contracture was examined using micro-computed tomography (micro-CT), however, only qualitative changes were reported. The aim of this study was to develop a quantitative method for comparing the shape changes of silicone implants using in vivo micro-CT. Mice were bilaterally implanted with silicone implants and underwent ionizing radiation to induce capsular contracture. On day 28 post-surgery mice were examined in vivo using micro-CT. The reconstructed cross-section images were visually inspected to identify distortion. Measurements were taken in 2D and 3D to quantify the shape of the implants in the normal (n = 11) and distorted (n = 5) groups. The degree of anisotropy was significantly higher in the distorted implants in the transaxial view (0.99 vs. 1.19, p = 0.002) and the y-axis lengths were significantly shorter in the sagittal (9.27 mm vs. 8.55 mm, p = 0.015) and coronal (9.24 mm vs. 8.76 mm, p = 0.031) views, indicating a deviation from the circular cross-section and shortening of the long axis. The 3D analysis revealed a significantly lower average thickness (sphere-fitting method) in distorted implants (6.86 mm vs. 5.49 mm, p = 0.002), whereas the volume and surface area did not show significant changes. Statistically significant differences between normal and distorted implants were found in 2D and 3D using distance measurements performed via micro-CT. This objective analysis method can be useful for a range of studies involving deformable implants using in vivo micro-CT. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1447-1452, 2017. © 2016 Wiley Periodicals, Inc.

MicroCT analysis of calcium/phosphorus ratio maps at different bone sites

International Nuclear Information System (INIS)

Speller, R.; Pani, S.; Tzaphlidou, M.; Horrocks, J.

2005-01-01

The Ca/P ratio was measured in cortical bone samples from the femoral neck, front and rear tibia of rats, rabbits and lambs using synchrotron microCT. Use of a monoenergetic X-ray beam, as provided by the synchrotron facility, generates accurate 3-D maps of the linear attenuation coefficient within the sample and hence gives the ability to map different chemical components. Data were taken at 20keV for each bone sample and calibration phantoms. From the 3-D data sets, multiple 2-D slices were reconstructed with a slice thickness of ∼28μm and converted to Ca/P ratios using the calibration phantom results. Average values for each animal and bone site were estimated. Differences between the same bone sites from different animals are not significant (0.3 -3 ) demonstrating a dependence upon lifestyle and bone use. The spatial distribution of Ca/P was found to be non-uniform for some bones and some animals possibly indicating the structural mechanism for obtaining bone strength

Auto calibration of a cone-beam-CT

International Nuclear Information System (INIS)

Gross, Daniel; Heil, Ulrich; Schulze, Ralf; Schoemer, Elmar; Schwanecke, Ulrich

2012-01-01

Purpose: This paper introduces a novel autocalibration method for cone-beam-CTs (CBCT) or flat-panel CTs, assuming a perfect rotation. The method is based on ellipse-fitting. Autocalibration refers to accurate recovery of the geometric alignment of a CBCT device from projection images alone, without any manual measurements. Methods: The authors use test objects containing small arbitrarily positioned radio-opaque markers. No information regarding the relative positions of the markers is used. In practice, the authors use three to eight metal ball bearings (diameter of 1 mm), e.g., positioned roughly in a vertical line such that their projection image curves on the detector preferably form large ellipses over the circular orbit. From this ellipse-to-curve mapping and also from its inversion the authors derive an explicit formula. Nonlinear optimization based on this mapping enables them to determine the six relevant parameters of the system up to the device rotation angle, which is sufficient to define the geometry of a CBCT-machine assuming a perfect rotational movement. These parameters also include out-of-plane rotations. The authors evaluate their method by simulation based on data used in two similar approaches [L. Smekal, M. Kachelriess, S. E, and K. Wa, “Geometric misalignment and calibration in cone-beam tomography,” Med. Phys. 31(12), 3242–3266 (2004); K. Yang, A. L. C. Kwan, D. F. Miller, and J. M. Boone, “A geometric calibration method for cone beam CT systems,” Med. Phys. 33(6), 1695–1706 (2006)]. This allows a direct comparison of accuracy. Furthermore, the authors present real-world 3D reconstructions of a dry human spine segment and an electronic device. The reconstructions were computed from projections taken with a commercial dental CBCT device having two different focus-to-detector distances that were both calibrated with their method. The authors compare their reconstruction with a reconstruction computed by the manufacturer of the

Methods of in-vivo mouse lung micro-CT

Science.gov (United States)

Recheis, Wolfgang A.; Nixon, Earl; Thiesse, Jacqueline; McLennan, Geoffrey; Ross, Alan; Hoffman, Eric

2005-04-01

Micro-CT will have a profound influence on the accumulation of anatomical and physiological phenotypic changes in natural and transgenetic mouse models. Longitudinal studies will be greatly facilitated, allowing for a more complete and accurate description of events if in-vivo studies are accomplished. The purpose of the ongoing project is to establish a feasible and reproducible setup for in-vivo mouse lung micro-computed tomography (μCT). We seek to use in-vivo respiratory-gated μCT to follow mouse models of lung disease with subsequent recovery of the mouse. Methodologies for optimizing scanning parameters and gating for the in-vivo mouse lung are presented. A Scireq flexiVent ventilated the gas-anesthetized mice at 60 breaths/minute, 30 cm H20 PEEP, 30 ml/kg tidal volume and provided a respiratory signal to gate a Skyscan 1076 μCT. Physiologic monitoring allowed the control of vital functions and quality of anesthesia, e.g. via ECG monitoring. In contrary to longer exposure times with ex-vivo scans, scan times for in-vivo were reduced using 35μm pixel size, 158ms exposure time and 18μm pixel size, 316ms exposure time to reduce motion artifacts. Gating via spontaneous breathing was also tested. Optimal contrast resolution was achieved at 50kVp, 200μA, applying an aluminum filter (0.5mm). There were minimal non-cardiac related motion artifacts. Both 35μm and 1μm voxel size images were suitable for evaluation of the airway lumen and parenchymal density. Total scan times were 30 and 65 minutes respectively. The mice recovered following scanning protocols. In-vivo lung scanning with recovery of the mouse delivered reasonable image quality for longitudinal studies, e.g. mouse asthma models. After examining 10 mice, we conclude μCT is a feasible tool evaluating mouse models of lung pathology in longitudinal studies with increasing anatomic detail available for evaluation as one moves from in-vivo to ex-vivo studies. Further developments include automated

A beam test of prototype time projection chamber using micro ...

Indian Academy of Sciences (India)

We conducted a series of beam tests of prototype TPCs for the international linear collider (ILC) experiment, equipped with an MWPC, a MicroMEGAS, or GEMs as a readout device. The prototype operated successfully in a test beam at KEK under an axial magnetic field of up to 1 T. The analysis of data is now in progress ...

Automated MicroSPECT/MicroCT Image Analysis of the Mouse Thyroid Gland.

Science.gov (United States)

Cheng, Peng; Hollingsworth, Brynn; Scarberry, Daniel; Shen, Daniel H; Powell, Kimerly; Smart, Sean C; Beech, John; Sheng, Xiaochao; Kirschner, Lawrence S; Menq, Chia-Hsiang; Jhiang, Sissy M

2017-11-01

The ability of thyroid follicular cells to take up iodine enables the use of radioactive iodine (RAI) for imaging and targeted killing of RAI-avid thyroid cancer following thyroidectomy. To facilitate identifying novel strategies to improve 131 I therapeutic efficacy for patients with RAI refractory disease, it is desired to optimize image acquisition and analysis for preclinical mouse models of thyroid cancer. A customized mouse cradle was designed and used for microSPECT/CT image acquisition at 1 hour (t1) and 24 hours (t24) post injection of 123 I, which mainly reflect RAI influx/efflux equilibrium and RAI retention in the thyroid, respectively. FVB/N mice with normal thyroid glands and TgBRAF V600E mice with thyroid tumors were imaged. In-house CTViewer software was developed to streamline image analysis with new capabilities, along with display of 3D voxel-based 123 I gamma photon intensity in MATLAB. The customized mouse cradle facilitates consistent tissue configuration among image acquisitions such that rigid body registration can be applied to align serial images of the same mouse via the in-house CTViewer software. CTViewer is designed specifically to streamline SPECT/CT image analysis with functions tailored to quantify thyroid radioiodine uptake. Automatic segmentation of thyroid volumes of interest (VOI) from adjacent salivary glands in t1 images is enabled by superimposing the thyroid VOI from the t24 image onto the corresponding aligned t1 image. The extent of heterogeneity in 123 I accumulation within thyroid VOIs can be visualized by 3D display of voxel-based 123 I gamma photon intensity. MicroSPECT/CT image acquisition and analysis for thyroidal RAI uptake is greatly improved by the cradle and the CTViewer software, respectively. Furthermore, the approach of superimposing thyroid VOIs from t24 images to select thyroid VOIs on corresponding aligned t1 images can be applied to studies in which the target tissue has differential radiotracer retention

The role of a microDiamond detector in the dosimetry of proton pencil beams

Energy Technology Data Exchange (ETDEWEB)

Goma, Carles [Paul Scherrer Institute, Villigen (Switzerland). Centre for Proton Therapy; Swiss Federal Institute of Technology Zurich (Switzerland). Dept. of Physics; Marinelli, Marco; Verona-Rinati, Gianluca [Roma Univ. ' ' Tor Vergata' ' (Italy). Dipt. di Ingegneria Industriale; INFN, Roma (Italy); Safai, Sairos [Paul Scherrer Institute, Villigen (Switzerland). Centre for Proton Therapy; Wuerfel, Jan [PTW-Freiburg, Freiburg (Germany)

2016-05-01

In this work, the performance of a microDiamond detector in a scanned proton beam is studied and its potential role in the dosimetric characterization of proton pencil beams is assessed. The linearity of the detector response with the absorbed dose and the dependence on the dose-rate were tested. The depth-dose curve and the lateral dose profiles of a proton pencil beam were measured and compared to reference data. The feasibility of calibrating the beam monitor chamber with a microDiamond detector was also studied. It was found the detector reading is linear with the absorbed dose to water (down to few cGy) and the detector response is independent of both the dose-rate (up to few Gy/s) and the proton beam energy (within the whole clinically-relevant energy range). The detector showed a good performance in depth-dose curve and lateral dose profile measurements; and it might even be used to calibrate the beam monitor chambers-provided it is cross-calibrated against a reference ionization chamber. In conclusion, the microDiamond detector was proved capable of performing an accurate dosimetric characterization of proton pencil beams.

Predicting factors for conversion from fluoroscopy guided Percutaneous transthoracic needle biopsy to cone-beam CT guided Percutaneous transthoracic needle biopsy

International Nuclear Information System (INIS)

Lee, Kang Ji; Han, Young Min; Jin, Gong Yong; Song, Ji Soo

2015-01-01

To evaluate the predicting factors for conversion from fluoroscopy guided percutaneous transthoracic needle biopsy (PTNB) to cone-beam CT guided PTNB. From January 2011 to December 2012, we retrospectively identified 38 patients who underwent cone-beam CT guided PTNB with solid pulmonary lesions, and 76 patients who underwent fluoroscopy guided PTNB were matched to the patients who underwent cone-beam CT guided PTNB for age, sex, and lesion location. We evaluated predicting factors such as, long-axis diameter, short-axis diameter, anterior-posterior diameter, and CT attenuation value of the solid pulmonary lesion affecting conversion from fluoroscopy guided PTNB to cone-beam CT guided PTNB. Pearson χ 2 test, Fisher exact test, and independent t test were used in statistical analyses; in addition, we also used receiver operating characteristics curve to find the proper cut-off values affecting the conversion to cone-beam CT guided PTNB. Short-axis, long-axis, anterior-posterior diameter and CT attenuation value of the solid pulmonary lesion in patients who underwent fluoroscopy guided PTNB were 2.70 ± 1.57 cm, 3.40 ± 1.92 cm, 3.06 ± 1.81 cm, and 35.67 ± 15.70 Hounsfield unit (HU), respectively. Short-axis, long-axis, anterior-posterior diameter and CT attenuation value of the solid pulmonary lesion in patients who underwent cone-beam CT guided PTNB were 1.60 ± 1.30 cm, 2.20 ± 1.45 cm, 1.91 ± 1.99 cm, and 18.32 ± 23.11 HU, respectively. Short-axis, long-axis, anterior-posterior diameter, and CT attenuation value showed a significantly different mean value between the 2 groups (p = 0.001, p < 0.001, p = 0.003, p < 0.001, respectively). Odd ratios of CT attenuation value and short-axis diameter of the solid pulmonary lesion were 0.952 and 0.618, respectively. Proper cut-off values affecting the conversion to cone-beam CT guided PTNB were 1.65 cm (sensitivity 68.4%, specificity 71.1%) in short-axis diameter and 29.50 HU (sensitivity 65.8%, specificity 65.8%) in

Applying microCT and 3D visualization to Jurassic silicified conifer seed cones: A virtual advantage over thin-sectioning.

Science.gov (United States)

Gee, Carole T

2013-11-01

As an alternative to conventional thin-sectioning, which destroys fossil material, high-resolution X-ray computed tomography (also called microtomography or microCT) integrated with scientific visualization, three-dimensional (3D) image segmentation, size analysis, and computer animation is explored as a nondestructive method of imaging the internal anatomy of 150-million-year-old conifer seed cones from the Late Jurassic Morrison Formation, USA, and of recent and other fossil cones. • MicroCT was carried out on cones using a General Electric phoenix v|tome|x s 240D, and resulting projections were processed with visualization software to produce image stacks of serial single sections for two-dimensional (2D) visualization, 3D segmented reconstructions with targeted structures in color, and computer animations. • If preserved in differing densities, microCT produced images of internal fossil tissues that showed important characters such as seed phyllotaxy or number of seeds per cone scale. Color segmentation of deeply embedded seeds highlighted the arrangement of seeds in spirals. MicroCT of recent cones was even more effective. • This is the first paper on microCT integrated with 3D segmentation and computer animation applied to silicified seed cones, which resulted in excellent 2D serial sections and segmented 3D reconstructions, revealing features requisite to cone identification and understanding of strobilus construction.

New development of integrated CT simulation system for radiation therapy planning

International Nuclear Information System (INIS)

Kushima, Takeyuki; Kono, Michio

1993-01-01

In order to put more accurate radiotherapy into practice, a radiotherapy planning system using CT, which is named CT simulation system, has been developed and introduced at Kobe University Hospital. The CT simulation system consists of a CT scanner, an image processing work-station, and a laser marking system. The target area of radiation is determined on each CT axial image of scout view in the work-station. Three-dimensional treatment planning is feasible on the basis of the two-dimensional tumor information in CT axial images. After setting treatment parameters, the contour of the radiation field on beam's eye view and the iso-center position are calculated by computer. This system makes it possible to choose an appropriate irradiation method and an optimal dose distribution. In the present study we examined the fundamental capability of this system. The laser marking system proved to have a very high degree of accuracy. The outcome of a phantom test raised the strong possibility that this system may be applied clinically. In addition to these basic findings, this paper describes preliminary clinical observations that support the good reproducibility of the radiation field projected with the CT simulator. In conclusion, this system is of high value for radiation therapy planning. (author)

Passive breath gating equipment for cone beam CT-guided RapidArc gastric cancer treatments

International Nuclear Information System (INIS)

Hu, Weigang; Li, Guichao; Ye, Jinsong; Wang, Jiazhou; Peng, Jiayuan; Gong, Min; Yu, Xiaoli; Studentski, Matthew T.; Xiao, Ying; Zhang, Zhen

2015-01-01

Background and purpose: To report preliminary results of passive breath gating (PBG) equipment for cone-beam CT image-guided gated RapidArc gastric cancer treatments. Material and methods: Home-developed PBG equipment integrated with the real-time position management system (RPM) for passive patient breath hold was used in CT simulation, online partial breath hold (PBH) CBCT acquisition, and breath-hold gating (BHG) RapidArc delivery. The treatment was discontinuously delivered with beam on during BH and beam off for free breathing (FB). Pretreatment verification PBH CBCT was obtained with the PBG-RPM system. Additionally, the reproducibility of the gating accuracy was evaluated. Results: A total of 375 fractions of breath-hold gating RapidArc treatments were successfully delivered and 233 PBH CBCTs were available for analysis. The PBH CBCT images were acquired with 2–3 breath holds and 1–2 FB breaks. The imaging time was the same for PBH CBCT and conventional FB CBCT (60 s). Compared to FB CBCT, the motion artifacts seen in PBH CBCT images were remarkably reduced. The average BHG RapidArc delivery time was 103 s for one 270-degree arc and 269 s for two full arcs. Conclusions: The PBG-RPM based PBH CBCT verification and BHG RapidArc delivery was successfully implemented clinically. The BHG RapidArc treatment was accomplished using a conventional RapidArc machine with high delivery efficiency

Application of microCT to the non-destructive testing of an additive manufactured titanium component

Directory of Open Access Journals (Sweden)

Anton du Plessis

2015-11-01

Full Text Available In this paper the application of X-ray microCT to the non-destructive testing of an additive manufactured titanium alloy component of complex geometry is demonstrated. Additive manufacturing of metal components is fast growing and shows great promise, yet these parts may contain defects which affect mechanical properties of the components. In this work a layered form of defect is found by microCT, which would have been very difficult or impossible to detect by other non-destructive testing methods due to the object complexity, defect size and shape and because the pores are entirely contained inside the object and not connected to the surface. Additionally, this test part was subjected to hot isostatic pressing (HIPPING and subsequently scanned. Comparing before and after scans by alignment of the volumes allows visualization and quantification of the pore size changes. The application of X-ray microCT to additive manufacturing is thus demonstrated in this example to be an ideal combination, especially for process improvements and for high value components.

Exploiting the potential of free software to evaluate root canal biomechanical preparation outcomes through micro-CT images.

Science.gov (United States)

Neves, A A; Silva, E J; Roter, J M; Belladona, F G; Alves, H D; Lopes, R T; Paciornik, S; De-Deus, G A

2015-11-01

To propose an automated image processing routine based on free software to quantify root canal preparation outcomes in pairs of sound and instrumented roots after micro-CT scanning procedures. Seven mesial roots of human mandibular molars with different canal configuration systems were studied: (i) Vertucci's type 1, (ii) Vertucci's type 2, (iii) two individual canals, (iv) Vertucci's type 6, canals (v) with and (vi) without debris, and (vii) canal with visible pulp calcification. All teeth were instrumented with the BioRaCe system and scanned in a Skyscan 1173 micro-CT before and after canal preparation. After reconstruction, the instrumented stack of images (IS) was registered against the preoperative sound stack of images (SS). Image processing included contrast equalization and noise filtering. Sound canal volumes were obtained by a minimum threshold. For the IS, a fixed conservative threshold was chosen as the best compromise between instrumented canal and dentine whilst avoiding debris, resulting in instrumented canal plus empty spaces. Arithmetic and logical operations between sound and instrumented stacks were used to identify debris. Noninstrumented dentine was calculated using a minimum threshold in the IS and subtracting from the SS and total debris. Removed dentine volume was obtained by subtracting SS from IS. Quantitative data on total debris present in the root canal space after instrumentation, noninstrumented areas and removed dentine volume were obtained for each test case, as well as three-dimensional volume renderings. After standardization of acquisition, reconstruction and image processing micro-CT images, a quantitative approach for calculation of root canal biomechanical outcomes was achieved using free software. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

The Final Focus Test Beam laser referene system

International Nuclear Information System (INIS)

Bressler, V.E.; Ruland, R.E.

1993-05-01

The original design for the SLAC linac included an alignment reference system with 270 diffraction gratings situated along the 3000 meter linac. These gratings have provided SLAC with a global reference line repeatable to within 200 micro meters. For the Final Focus Test Beam, this laser system has been extended and 13 new diffraction gratings have been installed. Improvements targets and the availability of new instruments allows us to evaluate the performance of the laser reference system at the 510 micro meter level. An explanation of the system and the results of our evaluation are presented

3D printing from microfocus computed tomography (micro-CT) in human specimens: education and future implications.

Science.gov (United States)

Shelmerdine, Susan C; Simcock, Ian C; Hutchinson, John Ciaran; Aughwane, Rosalind; Melbourne, Andrew; Nikitichev, Daniil I; Ong, Ju-Ling; Borghi, Alessandro; Cole, Garrard; Kingham, Emilia; Calder, Alistair D; Capelli, Claudio; Akhtar, Aadam; Cook, Andrew C; Schievano, Silvia; David, Anna; Ourselin, Sebastian; Sebire, Neil J; Arthurs, Owen J

2018-06-14

Microfocus CT (micro-CT) is an imaging method that provides three-dimensional digital data sets with comparable resolution to light microscopy. Although it has traditionally been used for non-destructive testing in engineering, aerospace industries and in preclinical animal studies, new applications are rapidly becoming available in the clinical setting including post-mortem fetal imaging and pathological specimen analysis. Printing three-dimensional models from imaging data sets for educational purposes is well established in the medical literature, but typically using low resolution (0.7 mm voxel size) data acquired from CT or MR examinations. With higher resolution imaging (voxel sizes below 1 micron, printing of micro-CT imaged specimens can provide insight into craniofacial surgical applications, developmental cardiac anatomy, placental imaging, archaeological remains and high-resolution bone imaging. We conclude with other potential future usages of this emerging technique.

MicroComputed Tomography: Methodology and Applications

International Nuclear Information System (INIS)

Stock, Stuart R.

2009-01-01

Due to the availability of commercial laboratory systems and the emergence of user facilities at synchrotron radiation sources, studies of microcomputed tomography or microCT have increased exponentially. MicroComputed Technology provides a complete introduction to the technology, describing how to use it effectively and understand its results. The first part of the book focuses on methodology, covering experimental methods, data analysis, and visualization approaches. The second part addresses various microCT applications, including porous solids, microstructural evolution, soft tissue studies, multimode studies, and indirect analyses. The author presents a sufficient amount of fundamental material so that those new to the field can develop a relative understanding of how to design their own microCT studies. One of the first full-length references dedicated to microCT, this book provides an accessible introduction to field, supplemented with application examples and color images.

Light ion microbeam analysis / processing system and its improvement

International Nuclear Information System (INIS)

Koka, Masashi; Ishii, Yasuyuki; Yamada, Naoto; Ohkubo, Takeru; Kamiya, Tomihiro; Satoh, Takahiro; Kada, Wataru; Kitamura, Akane; Iwata, Yoshihiro

2016-03-01

A MeV-class light ion microbeam system has been developed for micro-analysis and micro-fabrication with high spatial resolution at 3-MV single-ended accelerator in Takasaki Ion Accelerators for Advanced Radiation Application of Takasaki Advanced Radiation Research Institute, Sector of Nuclear Science Research, Japan Atomic Energy Agency. This report describes the technical improvements for the main apparatus (the accelerator, beam-transport lines, and microbeam system), and auxiliary equipments/ parts for ion beam applications such as Particle Induced X-ray/Gamma-ray Emission (PIXE/PIGE) analysis, 3-D element distribution analysis using PIXE Computed Tomography (CT), Ion Beam Induced Luminescence (IBIL) analysis, and Proton Beam Writing with the microbeam scanning, with functional outline of these apparatus and equipments/parts. (author)

Fabrication of micro-prominences on PTFE surface using proton beam writing

Energy Technology Data Exchange (ETDEWEB)

Kitamura, Akane, E-mail: ogawa.akane@jaea.go.jp [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-Machi, Takasaki, Gunma 370-1292 (Japan); Satoh, Takahiro; Koka, Masashi [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-Machi, Takasaki, Gunma 370-1292 (Japan); Kobayashi, Tomohiro [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 350-0198 (Japan); Kamiya, Tomihiro [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-Machi, Takasaki, Gunma 370-1292 (Japan)

2013-07-01

Polytetrafluoroethylene (PTFE) is a typical fluoropolymer and it has several desirable technological properties such as electrical insulation, solid lubrication etc. However, the conventional microstructuring methods have not been well applied to PTFE due to its chemical inertness. Some effective micromachining using synchrotron radiation or ion beam irradiation has been reported. In this study, we create micro-prominences by raising the original surface using proton beam writing (PBW) without chemical etching. A conical prominence was formed by spiral drawing from the center with a 3 MeV proton beam. The body was porous, and the bulk PTFE below the prominence changed to fragmented structures. With decreasing writing speed, the prominence became taller but the height peaked. The prominence gradually reduced in size after the speed reached the optimum value. We expect that these porous projections with high aspect ratio will be versatile in medical fields and microelectromechanical systems (MEMS) technology.

A Micro-Force Sensor with Beam-Membrane Structure for Measurement of Friction Torque in Rotating MEMS Machines

Directory of Open Access Journals (Sweden)

Huan Liu

2017-10-01

Full Text Available In this paper, a beam-membrane (BM sensor for measuring friction torque in micro-electro-mechanical system (MEMS gas bearings is presented. The proposed sensor measures the force-arm-transformed force using a detecting probe and the piezoresistive effect. This solution incorporates a membrane into a conventional four-beam structure to meet the range requirements for the measurement of both the maximum static friction torque and the kinetic friction torque in rotating MEMS machines, as well as eliminate the problem of low sensitivity with neat membrane structure. A glass wafer is bonded onto the bottom of the sensor chip with a certain gap to protect the sensor when overloaded. The comparisons between the performances of beam-based sensor, membrane-based sensor and BM sensor are conducted by finite element method (FEM, and the final sensor dimensions are also determined. Calibration of the fabricated and packaged device is experimentally performed. The practical verification is also reported in the paper for estimating the friction torque in micro gas bearings by assembling the proposed sensor into a rotary table-based measurement system. The results demonstrate that the proposed force sensor has a potential application in measuring micro friction or force in MEMS machines.

A DSP-Based Beam Current Monitoring System for Machine Protection Using Adaptive Filtering

International Nuclear Information System (INIS)

J. Musson; H. Dong; R. Flood; C. Hovater; J. Hereford

2001-01-01

The CEBAF accelerator at Jefferson Lab is currently using an analog beam current monitoring (BCM) system for its machine protection system (MPS), which has a loss accuracy of 2 micro-amps. Recent burn-through simulations predict catastrophic beam line component failures below 1 micro-amp of loss, resulting in a blind spot for the MPS. Revised MPS requirements target an ultimate beam loss accuracy of 250 nA. A new beam current monitoring system has been developed which utilizes modern digital receiver technology and digital signal processing concepts. The receiver employs a direct-digital down converter integrated circuit, mated with a Jefferson Lab digital signal processor VME card. Adaptive filtering is used to take advantage of current-dependent burn-through rates. Benefits of such a system include elimination of DC offsets, generic algorithm development, extensive filter options, and interfaces to UNIX-based control systems

A One-Step Cone-Beam CT-Enabled Planning-to-Treatment Model for Palliative Radiotherapy-From Development to Implementation

International Nuclear Information System (INIS)

Wong, Rebecca K.S.; Letourneau, Daniel; Varma, Anita; Bissonnette, Jean Pierre; Fitzpatrick, David; Grabarz, Daniel; Elder, Christine; Martin, Melanie; Bezjak, Andrea; Panzarella, Tony; Gospodarowicz, Mary; Jaffray, David A.

2012-01-01

Purpose: To develop a cone-beam computed tomography (CT)–enabled one-step simulation-to-treatment process for the treatment of bone metastases. Methods and Materials: A three-phase prospective study was conducted. Patients requiring palliative radiotherapy to the spine, mediastinum, or abdomen/pelvis suitable for treatment with simple beam geometry (≤2 beams) were accrued. Phase A established the accuracy of cone-beam CT images for the purpose of gross tumor target volume (GTV) definition. Phase B evaluated the feasibility of implementing the cone-beam CT–enabled planning process at the treatment unit. Phase C evaluated the online cone-beam CT–enabled process for the planning and treatment of patients requiring radiotherapy for bone metastases. Results: Eighty-four patients participated in this study. Phase A (n = 9) established the adequacy of cone-beam CT images for target definition. Phase B (n = 45) established the quality of treatment plans to be adequate for clinical implementation for bone metastases. When the process was applied clinically in bone metastases (Phase C), the degree of overlap between planning computed tomography (PCT) and cone-beam CT for GTV and between PCT and cone-beam CT for treatment field was 82% ± 11% and 97% ± 4%, respectively. The oncologist’s decision to accept the plan under a time-pressured environment remained of high quality, with the cone-beam CT–generated treatment plan delivering at least 90% of the prescribed dose to 100% ± 0% of the cone-beam CT planning target volume (PTV). With the assumption that the PCT PTV is the gold-standard target, the cone-beam CT–generated treatment plan delivered at least 90% and at least 95% of dose to 98% ± 2% and 97% ± 5% of the PCT PTV, respectively. The mean time for the online planning and treatment process was 32.7 ± 4.0 minutes. Patient satisfaction was high, with a trend for superior satisfaction with the cone-beam CT–enabled process. Conclusions: The cone-beam CT�

High resolution micro-CT scanning as an innovative tool for evaluation of the surgical positioning of cochlear implant electrodes.

Science.gov (United States)

Postnov, A; Zarowski, A; De Clerck, N; Vanpoucke, F; Offeciers, F E; Van Dyck, D; Peeters, S

2006-05-01

X-ray microtomography (micro-CT) is a new technique allowing for visualization of the internal structure of opaque specimens with a quasi-histological quality. Among multiple potential applications, the use of this technique in otology is very promising. Micro-CT appears to be ideally suited for in vitro visualization of the inner ear tissues as well as for evaluation of the electrode damage and/or surgical insertion trauma during implantation of the cochlear implant electrodes. This technique can greatly aid in design and development of new cochlear implant electrodes and is applicable for temporal bone studies. The main advantage of micro-CT is the practically artefact-free preparation of the samples and the possibility of evaluation of the interesting parameters along the whole insertion depth of the electrode. This paper presents the results of the first application of micro-CT for visualization of the inner ear structures in human temporal bones and for evaluation of the surgical positioning of the cochlear implant electrodes relative to the intracochlear soft tissues.

Dynamic pull-in instability of geometrically nonlinear actuated micro-beams based on the modified couple stress theory

Directory of Open Access Journals (Sweden)

Hamid M. Sedighi

Full Text Available This paper investigates the dynamic pull-in instability of vibrating micro-beams undergoing large deflection under electrosatically actuation. The governing equation of motion is derived based on the modified couple stress theory. Homotopy Perturbation Method is employed to produce the high accuracy approximate solution as well as the second-order frequency- amplitude relationship. The nonlinear governing equation of micro beam vibrations predeformed by an electric field includes both even and odd nonlinearities. The influences of basic non-dimensional parameters on the pull-in instability as well as the natural frequency are studied. It is demonstrated that two terms in series expansions are sufficient to produce high accuracy solution of the micro-structure. The accuracy of proposed asymptotic approach is validated via numerical results. The phase portrait of the system exhibits periodic and homoclinic orbits.

Alignment of dipole magnet in micro-beam line of HIRFL

International Nuclear Information System (INIS)

Wang Shaoming; Chen Wenjun; Yang Shengli; Cai Guozhu; Guo Yizhen; Zhou Guangming; Man Kaidi; Song Mingtao

2010-01-01

Microbeam irradiation facility is an experiment platform, which can reduce the beam-spot on the irradiated sample to micrometer level, and can accurately locate and count the radioactive particles. It is a powerful research tool for the irradiation material science, irradiation biology, irradiation biomedicine and micro mechanical machining. The microbeam irradiation facility requires the precise work for installation and alignment. These conditions make magnet's change for directions and positions because the location space of dipole magnets in micro-beam line of HIRFL (Heavy Ion Research Facility in Lanzhou) is very small. It is a challenge for the installation and alignment work of magnets. It was solved by transforming coordinates of benchmarks of magnets, which controlled the error of magnet setup within error tolerance range. (authors)

Assessment of scaffold porosity: the new route of micro-CT.

Science.gov (United States)

Bertoldi, Serena; Farè, Silvia; Tanzi, Maria Cristina

2011-01-01

A complete morphologic characterization of porous scaffolds for tissue engineering application is fundamental, as the architectural parameters, in particular porosity, strongly affect the mechanical and biological performance of the structures. Therefore, appropriate techniques for this purpose need to be selected. Several techniques for the assessment of scaffold porosity have been proposed, including Scanning Electron Microscopy observation, mercury and liquid extrusion porosimetry, gas pycnometry, and capillary flow porometry. Each of these techniques has several drawbacks and, a combination of different techniques is often required so as to achieve an in depth study of the morphologic properties of the scaffold. A single technique is often limited and suitable only for the assessment of a specific parameter. To overcome this limit, the most attractive option would be a single nondestructive technique, yet capable of providing a comprehensive set of data. It appears that micro-computed tomography (micro-CT) can potentially fulfill this role. Initially developed to characterize the 3D trabecular microarchitecture of bone, its use has been recently exploited by researchers for the morphologic characterization of porous biomaterials, as it enables obtaining a full assessment of the porous structures both in terms of pore size and interconnected porosity. This review aims to explore the use of micro-CT in scaffold characterization, comparing it with other previously developed techniques; we also focus on the contribution of this innovative tool to the development of scaffold-based tissue engineering application.

Dual resolution cone beam breast CT: A feasibility study

International Nuclear Information System (INIS)

Chen Lingyun; Shen Youtao; Lai, Chao-Jen; Han Tao; Zhong Yuncheng; Ge Shuaiping; Liu Xinming; Wang Tianpeng; Yang, Wei T.; Whitman, Gary J.; Shaw, Chris C.

2009-01-01

Purpose: In this study, the authors investigated the feasibility of a dual resolution volume-of-interest (VOI) cone beam breast CT technique and compared two implementation approaches in terms of dose saving and scatter reduction. Methods: With this technique, a lead VOI mask with an opening is inserted between the x-ray source and the breast to deliver x-ray exposure to the VOI while blocking x rays outside the VOI. A CCD detector is used to collect the high resolution projection data of the VOI. Low resolution cone beam CT (CBCT) images of the entire breast, acquired with a flat panel (FP) detector, were used to calculate the projection data outside the VOI with the ray-tracing reprojection method. The Feldkamp-Davis-Kress filtered backprojection algorithm was used to reconstruct the dual resolution 3D images. Breast phantoms with 180 μm and smaller microcalcifications (MCs) were imaged with both FP and FP-CCD dual resolution CBCT systems, respectively. Two approaches of implementing the dual resolution technique, breast-centered approach and VOI-centered approach, were investigated and evaluated for dose saving and scatter reduction with Monte Carlo simulation using a GEANT4 package. Results: The results showed that the breast-centered approach saved more breast absorbed dose than did VOI-centered approach with similar scatter reduction. The MCs in fatty breast phantom, which were invisible with FP CBCT scan, became visible with the FP-CCD dual resolution CBCT scan. Conclusions: These results indicate potential improvement of the image quality inside the VOI with reduced breast dose both inside and outside the VOI.

Longitudinal in vivo evaluation of bone regeneration by combined measurement of multi-pinhole SPECT and micro-CT for tissue engineering

Science.gov (United States)

Lienemann, Philipp S.; Metzger, Stéphanie; Kiveliö, Anna-Sofia; Blanc, Alain; Papageorgiou, Panagiota; Astolfo, Alberto; Pinzer, Bernd R.; Cinelli, Paolo; Weber, Franz E.; Schibli, Roger; Béhé, Martin; Ehrbar, Martin

2015-05-01

Over the last decades, great strides were made in the development of novel implants for the treatment of bone defects. The increasing versatility and complexity of these implant designs request for concurrent advances in means to assess in vivo the course of induced bone formation in preclinical models. Since its discovery, micro-computed tomography (micro-CT) has excelled as powerful high-resolution technique for non-invasive assessment of newly formed bone tissue. However, micro-CT fails to provide spatiotemporal information on biological processes ongoing during bone regeneration. Conversely, due to the versatile applicability and cost-effectiveness, single photon emission computed tomography (SPECT) would be an ideal technique for assessing such biological processes with high sensitivity and for nuclear imaging comparably high resolution (designed poly(ethylene glycol)-based hydrogels that release bone morphogenetic protein to guide the healing of critical sized calvarial bone defects. By combined in vivo longitudinal multi-pinhole SPECT and micro-CT evaluations we determine the spatiotemporal course of bone formation and remodeling within this synthetic hydrogel implant. End point evaluations by high resolution micro-CT and histological evaluation confirm the value of this approach to follow and optimize bone-inducing biomaterials.

Development of in-vivo micro CT system for small animals

Energy Technology Data Exchange (ETDEWEB)

Nam, Ki Yong; Lim, Jong Hyeok; Jeong, Young Jo; Park, Jeong Gwon [Institute for Radiological Imaging Science, Iksan (Korea, Republic of); Park, Jung Bung [DRGEM Corp., Seoul (Korea, Republic of); Yoon, Kwon Ha [Institute for Radiological Imaging Science and Medical School of Radiology, Iksan (Korea, Republic of)

2005-07-01

Computed tomography system with the spatial resolution of {approx}25 {mu}m has been developed for the application to small animals. This system is designed by gantry-rotation type for minimizing animal movement. To get image with micro-spatial resolution, system characteristic such as geometry between main components of source, specimen and detector, field of view, etc., is described in this paper. The requirements of x-ray spot size and CCD pixel size to approach the resolution are discussed. In-vivo imaging test for mouse is also presented as a result.

Development of in-vivo micro CT system for small animals

International Nuclear Information System (INIS)

Nam, Ki Yong; Lim, Jong Hyeok; Jeong, Young Jo; Park, Jeong Gwon; Park, Jung Bung; Yoon, Kwon Ha

2005-01-01

Computed tomography system with the spatial resolution of ∼25 μm has been developed for the application to small animals. This system is designed by gantry-rotation type for minimizing animal movement. To get image with micro-spatial resolution, system characteristic such as geometry between main components of source, specimen and detector, field of view, etc., is described in this paper. The requirements of x-ray spot size and CCD pixel size to approach the resolution are discussed. In-vivo imaging test for mouse is also presented as a result

Physical performance and image optimization of megavoltage cone-beam CT

Energy Technology Data Exchange (ETDEWEB)

Morin, Olivier; Aubry, Jean-Francois; Aubin, Michele; Chen, Josephine; Descovich, Martina; Hashemi, Ali-Bani; Pouliot, Jean [Department of Radiation Oncology, Helen Diller Comprehensive Cancer Center, University of California San Francisco, San Francisco, California 94143 and UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, California 94158 (United States); Department of Radiation Oncology, Helen Diller Comprehensive Cancer Center, University of California San Francisco, San Francisco, California 94143 (United States); Siemens Oncology Care Systems, Concord, California 94520 (United States); Department of Radiation Oncology, Helen Diller Comprehensive Cancer Center, University of California San Francisco, San Francisco, California 94143 and UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, California 94158 (United States)

2009-04-15

Megavoltage cone-beam CT (MVCBCT) is the most recent addition to the in-room CT systems developed for image-guided radiation therapy. The first generation MVCBCT system consists of a 6 MV treatment x-ray beam produced by a conventional linear accelerator equipped with a flat panel amorphous silicon detector. The objective of this study was to evaluate the physical performance of MVCBCT in order to optimize the system acquisition and reconstruction parameters for image quality. MVCBCT acquisitions were performed with the clinical system but images were reconstructed and analyzed with a separate research workstation. The geometrical stability and the positioning accuracy of the system were evaluated by comparing geometrical calibrations routinely performed over a period of 12 months. The beam output and detector intensity stability during MVCBCT acquisition were also evaluated by analyzing in-air acquisitions acquired at different exposure levels. Several system parameters were varied to quantify their impact on image quality including the exposure (2.7, 4.5, 9.0, 18.0, and 54.0 MU), the craniocaudal imaging length (2, 5, 15, and 27.4 cm), the voxel size (0.5, 1, and 2 mm), the slice thickness (1, 3, and 5 mm), and the phantom size. For the reconstruction algorithm, the study investigated the effect of binning, averaging and diffusion filtering of raw projections as well as three different projection filters. A head-sized water cylinder was used to measure and improve the uniformity of MVCBCT images. Inserts of different electron densities were placed in a water cylinder to measure the contrast-to-noise ratio (CNR). The spatial resolution was obtained by measuring the point-spread function of the system using an iterative edge blurring technique. Our results showed that the geometric stability and accuracy of MVCBCT were better than 1 mm over a period of 12 months. Beam intensity variations per projection of up to 35.4% were observed for a 2.7 MU MVCBCT acquisition

RHIC Beam Loss Monitor System Initial Operation

International Nuclear Information System (INIS)

Witkover, R. L.; Michnoff, R. J.; Geller, J. M.

1999-01-01

The RHIC Beam Loss Monitor (BLM) System is designed to prevent beam loss quenching of the superconducting magnets, and acquire loss data. Four hundred ion chambers are located around the rings to detect losses. The required 8-decade range in signal current is compressed using an RC pre-integrator ahead of a low current amplifier. A beam abort may be triggered if fast or slow losses exceed programmable threshold levels. A micro-controller based VME module sets references and gains and reads trip status for up to 64 channels. Results obtained with the detectors in the RHIC Sextant Test and the prototype electronics in the AGS-to-RHIC (AtR) transfer line are presented along with the present status of the system

Applying microCT and 3D visualization to Jurassic silicified conifer seed cones: A virtual advantage over thin-sectioning1

Science.gov (United States)

Gee, Carole T.

2013-01-01

• Premise of the study: As an alternative to conventional thin-sectioning, which destroys fossil material, high-resolution X-ray computed tomography (also called microtomography or microCT) integrated with scientific visualization, three-dimensional (3D) image segmentation, size analysis, and computer animation is explored as a nondestructive method of imaging the internal anatomy of 150-million-year-old conifer seed cones from the Late Jurassic Morrison Formation, USA, and of recent and other fossil cones. • Methods: MicroCT was carried out on cones using a General Electric phoenix v|tome|x s 240D, and resulting projections were processed with visualization software to produce image stacks of serial single sections for two-dimensional (2D) visualization, 3D segmented reconstructions with targeted structures in color, and computer animations. • Results: If preserved in differing densities, microCT produced images of internal fossil tissues that showed important characters such as seed phyllotaxy or number of seeds per cone scale. Color segmentation of deeply embedded seeds highlighted the arrangement of seeds in spirals. MicroCT of recent cones was even more effective. • Conclusions: This is the first paper on microCT integrated with 3D segmentation and computer animation applied to silicified seed cones, which resulted in excellent 2D serial sections and segmented 3D reconstructions, revealing features requisite to cone identification and understanding of strobilus construction. PMID:25202495

Automated assessment of bone changes in cross-sectional micro-CT studies of murine experimental osteoarthritis.

Science.gov (United States)

Das Neves Borges, Patricia; Vincent, Tonia L; Marenzana, Massimo

2017-01-01

The degradation of articular cartilage, which characterises osteoarthritis (OA), is usually paired with excessive bone remodelling, including subchondral bone sclerosis, cysts, and osteophyte formation. Experimental models of OA are widely used to investigate pathogenesis, yet few validated methodologies for assessing periarticular bone morphology exist and quantitative measurements are limited by manual segmentation of micro-CT scans. The aim of this work was to chart the temporal changes in periarticular bone in murine OA by novel, automated micro-CT methods. OA was induced by destabilisation of the medial meniscus (DMM) in 10-week old male mice and disease assessed cross-sectionally from 1- to 20-weeks post-surgery. A novel approach was developed to automatically segment subchondral bone compartments into plate and trabecular bone in micro-CT scans of tibial epiphyses. Osteophyte volume, as assessed by shape differences using 3D image registration, and by measuring total epiphyseal volume was performed. Significant linear and volumetric structural modifications in subchondral bone compartments and osteophytes were measured from 4-weeks post-surgery and showed progressive changes at all time points; by 20 weeks, medial subchondral bone plate thickness increased by 160±19.5 μm and the medial osteophyte grew by 0.124±0.028 μm3. Excellent agreement was found when automated measurements were compared with manual assessments. Our automated methods for assessing bone changes in murine periarticular bone are rapid, quantitative, and highly accurate, and promise to be a useful tool in future preclinical studies of OA progression and treatment. The current approaches were developed specifically for cross-sectional micro-CT studies but could be applied to longitudinal studies.

Automated assessment of bone changes in cross-sectional micro-CT studies of murine experimental osteoarthritis.

Directory of Open Access Journals (Sweden)

Patricia Das Neves Borges

Full Text Available The degradation of articular cartilage, which characterises osteoarthritis (OA, is usually paired with excessive bone remodelling, including subchondral bone sclerosis, cysts, and osteophyte formation. Experimental models of OA are widely used to investigate pathogenesis, yet few validated methodologies for assessing periarticular bone morphology exist and quantitative measurements are limited by manual segmentation of micro-CT scans. The aim of this work was to chart the temporal changes in periarticular bone in murine OA by novel, automated micro-CT methods.OA was induced by destabilisation of the medial meniscus (DMM in 10-week old male mice and disease assessed cross-sectionally from 1- to 20-weeks post-surgery. A novel approach was developed to automatically segment subchondral bone compartments into plate and trabecular bone in micro-CT scans of tibial epiphyses. Osteophyte volume, as assessed by shape differences using 3D image registration, and by measuring total epiphyseal volume was performed.Significant linear and volumetric structural modifications in subchondral bone compartments and osteophytes were measured from 4-weeks post-surgery and showed progressive changes at all time points; by 20 weeks, medial subchondral bone plate thickness increased by 160±19.5 μm and the medial osteophyte grew by 0.124±0.028 μm3. Excellent agreement was found when automated measurements were compared with manual assessments.Our automated methods for assessing bone changes in murine periarticular bone are rapid, quantitative, and highly accurate, and promise to be a useful tool in future preclinical studies of OA progression and treatment. The current approaches were developed specifically for cross-sectional micro-CT studies but could be applied to longitudinal studies.

Spatial beam shaping using a micro-structured optical fiber and all-fiber laser amplification system for large-scale laser facilities seeding

International Nuclear Information System (INIS)

Calvet, Pierre

2014-01-01

Spatial beam shaping is an important topic for the lasers applications. For various industrial areas (marking, drilling, laser-matter interaction, high-power laser seeding...) the optical beam has to be flattened. Currently, the state of the art of the beam shaping: 'free-space' solutions or highly multimode fibers, are not fully suitable. The first ones are very sensitive to any perturbations and the maintenance is challenging, the second ones cannot deliver a coherent beam. For this reason, we present in this manuscript a micro-structured optical single-mode fiber delivering a spatially flattened beam. This 'Top-Hat' fiber can shape any beam in a spatially coherent beam what is a progress with respect to the highly multimode fibers used in the state of the art. The optical fibers are easy to use and very robust, what is a strong benefit with respect to the 'free-space' solutions. Thanks to this fiber, we could realize an all-fiber multi-stage laser chain to amplify a 10 ns pulse to 100 μJ. Moreover the temporal, spectral and spatial properties were preserved. We adapted this 'Top-Hat' fiber to this multi-stage laser chain, we proved the capability and the interest of this fiber for the spatial beam shaping of the laser beams in highly performing and robust laser systems. (author) [fr

Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and Monte Carlo simulations.

Science.gov (United States)

Kim, Sangroh; Yoshizumi, Terry T; Toncheva, Greta; Frush, Donald P; Yin, Fang-Fang

2010-03-01

The purpose of this study was to establish a dose estimation tool with Monte Carlo (MC) simulations. A 5-y-old paediatric anthropomorphic phantom was computed tomography (CT) scanned to create a voxelised phantom and used as an input for the abdominal cone-beam CT in a BEAMnrc/EGSnrc MC system. An X-ray tube model of the Varian On-Board Imager((R)) was built in the MC system. To validate the model, the absorbed doses at each organ location for standard-dose and low-dose modes were measured in the physical phantom with MOSFET detectors; effective doses were also calculated. In the results, the MC simulations were comparable to the MOSFET measurements. This voxelised phantom approach could produce a more accurate dose estimation than the stylised phantom method. This model can be easily applied to multi-detector CT dosimetry.

Flexible, ionic liquid-based micro-supercapacitor produced by supersonic cluster beam deposition

International Nuclear Information System (INIS)

Bettini, L.G.; Piseri, P.; De Giorgio, F.; Arbizzani, C.; Milani, P.; Soavi, F.

2015-01-01

Highlights: • We exploited Supersonic Cluster Beam Deposition for the fabrication of a flexible, planar micro-supercapacitor featuring nanostructured carbon electrodes deposited on a plastic Mylar substrate and N-trimethyl-N-propyl-ammonium bis(trifluoromethanesulfonyl) imide (N 1113 TFSI) ionic liquid electrolyte. • The micro-supercapacitor operates at 3 V above RT up to 80 °C with a capacitance density approaching 10 F cm −3 and delivering maximum specific energy and power densities of 10 mWh cm −3 and 8-10 W cm −3 . • The micro-supercapacitor features long cycling stability over 2x10 4 cycle on flat and bent configuration. -- Graphical abstract: Display Omitted -- Abstract: Power generation and storage in electronics require flexible, thin micro-electrochemical energy storage/conversion systems. Micro-supercapacitors (μSCs) with double-layer capacitance carbon electrodes are attracting much attention for their capability of delivering short power pulses with high stability over repeated charge/discharge cycling. Supersonic Cluster Beam Deposition (SCBD) is an effective strategy for the development of nanostructured, binder-free porous carbon electrodes on temperature sensitive substrates including polymers. We exploited SCBD for the development of a flexible, planar μSC featuring nanostructured carbon (ns-C) electrodes deposited on a plastic Mylar substrate and N-trimethyl-N-propyl-ammonium bis(trifluoromethanesulfonyl) imide (N 1113 TFSI) ionic liquid electrolyte. The electrochemical performance at different temperatures of the μSC which operates at 3 V above RT up to 80 °C with a capacitance density approaching 10 F cm −3 and delivering maximum specific energy and power densities of 10 mWh cm −3 and 8-10 W cm −3 with long cycling stability over 2 × 10 4 cycles is here reported and discussed

Using Micro-CT Derived Bone Microarchitecture to Analyze Bone Stiffness - A Case Study on Osteoporosis Rat Bone

Directory of Open Access Journals (Sweden)

Yuchin eWu

2015-05-01

Full Text Available Micro-computed tomography images can be used to quantitatively represent bone geometry through a range of computed attenuation-based parameters. Nonetheless, those parameters remain indirect indices of bone micro-architectural strength and require further computational tools to interpret bone structural stiffness and potential for mechanical failure. Finite element analysis (FEA can be applied to measure trabecular bone stiffness and potentially predict the location of structural failure in preclinical animal models of osteoporosis, although that procedure from image segmentation of micro-CT derived bone geometry to FEA is often challenging and computationally expensive, resulting in failure of the model to build. Notably, the selection of resolution and threshold for bone segmentation are key steps that greatly affect computational complexity and validity. In the following study, we evaluated an approach whereby Micro-CT derived greyscale attenuation and segmentation data guided the selection of trabecular bone for analysis by FEA. We further correlated those FEA results to both two and three dimensional bone microarchitecture from sham and ovariectomized (OVX rats (n=10/group. A virtual cylinder of vertebral trabecular bone 40% in length from the caudal side was selected for FEA because micro-CT based image analysis indicated the largest differences in microarchitecture between the two groups resided there. Bone stiffness was calculated using FEA and statistically correlated with the three dimensional values of bone volume/tissue volume, bone mineral density, fractal dimension, trabecular separation and trabecular bone pattern factor. Our method simplified the process for the assessment of trabecular bone stiffness by FEA from Micro-CT images and highlighted the importance of bone microarchitecture in conferring significantly increased bone quality capable of resisting failure due to increased mechanical loading.

Toward acquiring comprehensive radiosurgery field commissioning data using the PRESAGE/optical-CT 3D dosimetry system

Energy Technology Data Exchange (ETDEWEB)

Clift, Corey; Thomas, Andrew; Chang Zheng; Oldham, Mark [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Adamovics, John [Department of Chemistry, Rider University, Lawrenceville, NJ 08648 (United States); Das, Indra [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN 46202 (United States)], E-mail: cclift@montefiore.org

2010-03-07

Achieving accurate small field dosimetry is challenging. This study investigates the utility of a radiochromic plastic PRESAGE read with optical-CT for the acquisition of radiosurgery field commissioning data from a Novalis Tx system with a high-definition multileaf collimator (HDMLC). Total scatter factors (S{sub c,p}), beam profiles, and penumbrae were measured for five different radiosurgery fields (5, 10, 20, 30 and 40 mm) using a commercially available optical-CT scanner (OCTOPUS, MGS Research). The percent depth dose (PDD), beam profile and penumbra of the 10 mm field were also measured using a higher resolution in-house prototype CCD-based scanner. Gafchromic EBT film was used for independent verification. Measurements of S{sub c,p} made with PRESAGE and film agreed with mini-ion chamber commissioning data to within 4% for every field (range 0.2-3.6% for PRESAGE, and 1.6-3.6% for EBT). PDD, beam profile and penumbra measurements made with the two PRESAGE/optical-CT systems and film showed good agreement with the high-resolution diode commissioning measurements with a competitive resolution (0.5 mm pixels). The in-house prototype optical-CT scanner allowed much finer resolution compared with previous applications of PRESAGE. The advantages of the PRESAGE (registered) system for small field dosimetry include 3D measurements, negligible volume averaging, directional insensitivity, an absence of beam perturbations, energy and dose rate independence.

Toward acquiring comprehensive radiosurgery field commissioning data using the PRESAGE/optical-CT 3D dosimetry system

International Nuclear Information System (INIS)

Clift, Corey; Thomas, Andrew; Chang Zheng; Oldham, Mark; Adamovics, John; Das, Indra

2010-01-01

Achieving accurate small field dosimetry is challenging. This study investigates the utility of a radiochromic plastic PRESAGE read with optical-CT for the acquisition of radiosurgery field commissioning data from a Novalis Tx system with a high-definition multileaf collimator (HDMLC). Total scatter factors (S c,p ), beam profiles, and penumbrae were measured for five different radiosurgery fields (5, 10, 20, 30 and 40 mm) using a commercially available optical-CT scanner (OCTOPUS, MGS Research). The percent depth dose (PDD), beam profile and penumbra of the 10 mm field were also measured using a higher resolution in-house prototype CCD-based scanner. Gafchromic EBT film was used for independent verification. Measurements of S c,p made with PRESAGE and film agreed with mini-ion chamber commissioning data to within 4% for every field (range 0.2-3.6% for PRESAGE, and 1.6-3.6% for EBT). PDD, beam profile and penumbra measurements made with the two PRESAGE/optical-CT systems and film showed good agreement with the high-resolution diode commissioning measurements with a competitive resolution (0.5 mm pixels). The in-house prototype optical-CT scanner allowed much finer resolution compared with previous applications of PRESAGE. The advantages of the PRESAGE (registered) system for small field dosimetry include 3D measurements, negligible volume averaging, directional insensitivity, an absence of beam perturbations, energy and dose rate independence.

Toward acquiring comprehensive radiosurgery field commissioning data using the PRESAGE®/ optical-CT 3D dosimetry system

Science.gov (United States)

Clift, Corey; Thomas, Andrew; Adamovics, John; Chang, Zheng; Das, Indra; Oldham, Mark

2010-03-01

Achieving accurate small field dosimetry is challenging. This study investigates the utility of a radiochromic plastic PRESAGE® read with optical-CT for the acquisition of radiosurgery field commissioning data from a Novalis Tx system with a high-definition multileaf collimator (HDMLC). Total scatter factors (Sc, p), beam profiles, and penumbrae were measured for five different radiosurgery fields (5, 10, 20, 30 and 40 mm) using a commercially available optical-CT scanner (OCTOPUS, MGS Research). The percent depth dose (PDD), beam profile and penumbra of the 10 mm field were also measured using a higher resolution in-house prototype CCD-based scanner. Gafchromic EBT® film was used for independent verification. Measurements of Sc, p made with PRESAGE® and film agreed with mini-ion chamber commissioning data to within 4% for every field (range 0.2-3.6% for PRESAGE®, and 1.6-3.6% for EBT). PDD, beam profile and penumbra measurements made with the two PRESAGE®/optical-CT systems and film showed good agreement with the high-resolution diode commissioning measurements with a competitive resolution (0.5 mm pixels). The in-house prototype optical-CT scanner allowed much finer resolution compared with previous applications of PRESAGE®. The advantages of the PRESAGE® system for small field dosimetry include 3D measurements, negligible volume averaging, directional insensitivity, an absence of beam perturbations, energy and dose rate independence.

An index of beam hardening artifact for two-dimensional cone-beam CT tomographic images: establishment and preliminary evaluation

Science.gov (United States)

Yuan, Fusong; Lv, Peijun; Yang, Huifang; Wang, Yong; Sun, Yuchun

2015-07-01

Objectives: Based on the pixel gray value measurements, establish a beam-hardening artifacts index of the cone-beam CT tomographic image, and preliminarily evaluate its applicability. Methods: The 5mm-diameter metal ball and resin ball were fixed on the light-cured resin base plate respectively, while four vitro molars were fixed above and below the ball, on the left and right respectively, which have 10mm distance with the metal ball. Then, cone beam CT was used to scan the fixed base plate twice. The same layer tomographic images were selected from the two data and imported into the Photoshop software. The circle boundary was built through the determination of the center and radius of the circle, according to the artifact-free images section. Grayscale measurement tools were used to measure the internal boundary gray value G0, gray value G1 and G2 of 1mm and 20mm artifacts outside the circular boundary, the length L1 of the arc with artifacts in the circular boundary, the circumference L2. Hardening artifacts index was set A = (G1 / G0) * 0.5 + (G2 / G1) * 0.4 + (L2 / L1) * 0.1. Then, the A values of metal and resin materials were calculated respectively. Results: The A value of cobalt-chromium alloy material is 1, and resin material is 0. Conclusion: The A value reflects comprehensively the three factors of hardening artifacts influencing normal oral tissue image sharpness of cone beam CT. The three factors include relative gray value, the decay rate and range of artifacts.

Optimizing laser beam profiles using micro-lens arrays for efficient material processing: applications to solar cells

Science.gov (United States)

Hauschild, Dirk; Homburg, Oliver; Mitra, Thomas; Ivanenko, Mikhail; Jarczynski, Manfred; Meinschien, Jens; Bayer, Andreas; Lissotschenko, Vitalij

2009-02-01

High power laser sources are used in various production tools for microelectronic products and solar cells, including the applications annealing, lithography, edge isolation as well as dicing and patterning. Besides the right choice of the laser source suitable high performance optics for generating the appropriate beam profile and intensity distribution are of high importance for the right processing speed, quality and yield. For industrial applications equally important is an adequate understanding of the physics of the light-matter interaction behind the process. In advance simulations of the tool performance can minimize technical and financial risk as well as lead times for prototyping and introduction into series production. LIMO has developed its own software founded on the Maxwell equations taking into account all important physical aspects of the laser based process: the light source, the beam shaping optical system and the light-matter interaction. Based on this knowledge together with a unique free-form micro-lens array production technology and patented micro-optics beam shaping designs a number of novel solar cell production tool sub-systems have been built. The basic functionalities, design principles and performance results are presented with a special emphasis on resilience, cost reduction and process reliability.

Investigating the effect of longitudinal micro-CT imaging on tumour growth in mice

International Nuclear Information System (INIS)

Foster, W Kyle; Ford, Nancy L

2011-01-01

The aim of this study is to determine the impact of longitudinal micro-CT imaging on the growth of B16F1 tumours in C57BL/6 mice. Sixty mice received 2 x 10 5 B16F1 cells subcutaneously in the hind flank and were divided into control (no scan), 'low-dose' (80 kVp, 70 mA, 8 s, 0.07 Gy), 'medium-dose' (80 kVp, 50 mA, 30 s, 0.18 Gy) and 'high-dose' (80 kVp, 50 mA, 50 s, 0.30 Gy) groups. All imaging was performed on a fast volumetric micro-CT scanner (GE Locus Ultra, London, Canada). Each mouse was imaged on days 4, 8, 12 and 16. After the final imaging session, each tumour was excised, weighed on an electronic balance, imaged to obtain the final tumour volume and processed for histology. Final tumour volume was used to evaluate the impact of longitudinal micro-CT imaging on the tumour growth. An ANOVA indicated no statistically significant difference in tumour volume (p = 0.331, α = β = 0.1) when discriminating against a treatment-sized effect. Histological samples revealed no observable differences in apoptosis or cell proliferation. We conclude that four imaging sessions, using standard protocols, over the course of 16 days did not cause significant changes in final tumour volume for B16F1 tumours in female C57BL/6 mice (ANOVA, α = β = 0.1, p = 0.331).

A dedicated cone-beam CT system for musculoskeletal extremities imaging: Design, optimization, and initial performance characterization

International Nuclear Information System (INIS)

Zbijewski, W.; De Jean, P.; Prakash, P.; Ding, Y.; Stayman, J. W.; Packard, N.; Senn, R.; Yang, D.; Yorkston, J.; Machado, A.; Carrino, J. A.; Siewerdsen, J. H.

2011-01-01

Purpose: This paper reports on the design and initial imaging performance of a dedicated cone-beam CT (CBCT) system for musculoskeletal (MSK) extremities. The system complements conventional CT and MR and offers a variety of potential clinical and logistical advantages that are likely to be of benefit to diagnosis, treatment planning, and assessment of therapy response in MSK radiology, orthopaedic surgery, and rheumatology. Methods: The scanner design incorporated a host of clinical requirements (e.g., ability to scan the weight-bearing knee in a natural stance) and was guided by theoretical and experimental analysis of image quality and dose. Such criteria identified the following basic scanner components and system configuration: a flat-panel detector (FPD, Varian 3030+, 0.194 mm pixels); and a low-power, fixed anode x-ray source with 0.5 mm focal spot (SourceRay XRS-125-7K-P, 0.875 kW) mounted on a retractable C-arm allowing for two scanning orientations with the capability for side entry, viz. a standing configuration for imaging of weight-bearing lower extremities and a sitting configuration for imaging of tensioned upper extremity and unloaded lower extremity. Theoretical modeling employed cascaded systems analysis of modulation transfer function (MTF) and detective quantum efficiency (DQE) computed as a function of system geometry, kVp and filtration, dose, source power, etc. Physical experimentation utilized an imaging bench simulating the scanner geometry for verification of theoretical results and investigation of other factors, such as antiscatter grid selection and 3D image quality in phantom and cadaver, including qualitative comparison to conventional CT. Results: Theoretical modeling and benchtop experimentation confirmed the basic suitability of the FPD and x-ray source mentioned above. Clinical requirements combined with analysis of MTF and DQE yielded the following system geometry: a ∼55 cm source-to-detector distance; 1.3 magnification; a 20

MicroCT analysis of calcium/phosphorus ratio maps at different bone sites

Energy Technology Data Exchange (ETDEWEB)

Speller, R. [Medical Physics and Bioengineering Department, UCL, London, WC1E 6BT (United Kingdom)]. E-mail: rspeller@medphys.ucl.ac.uk; Pani, S. [Department of Physics, University of Trieste (Italy); Tzaphlidou, M. [Lab Medical Physics, Medical School, University of Ioannina, 45110 Ioannina (Greece); Horrocks, J. [Clinical Physics Group, St Bartholomew' s Hospital, London, EC1A 6BT (United Kingdom)

2005-08-11

The Ca/P ratio was measured in cortical bone samples from the femoral neck, front and rear tibia of rats, rabbits and lambs using synchrotron microCT. Use of a monoenergetic X-ray beam, as provided by the synchrotron facility, generates accurate 3-D maps of the linear attenuation coefficient within the sample and hence gives the ability to map different chemical components. Data were taken at 20keV for each bone sample and calibration phantoms. From the 3-D data sets, multiple 2-D slices were reconstructed with a slice thickness of {approx}28{mu}m and converted to Ca/P ratios using the calibration phantom results. Average values for each animal and bone site were estimated. Differences between the same bone sites from different animals are not significant (0.3

Micro-vibration response of a stochastically excited sandwich beam with a magnetorheological elastomer core and mass

International Nuclear Information System (INIS)

Ying, Z G; Ni, Y Q

2009-01-01

Magnetorheological (MR) elastomers are used to construct a smart sandwich beam for micro-vibration control. The micro-vibration response of a clamped–free sandwich beam with an MR elastomer core and a supplemental mass under stochastic support micro-motion excitation is studied. The dynamic behavior of MR elastomer as a smart viscoelastic material is described by a complex modulus which is controllable by external magnetic field. The sixth-order partial differential equation of motion of the sandwich beam is derived from the dynamic equilibrium, constitutive and geometric relations. A frequency-domain solution method for the stochastic micro-vibration response of the sandwich beam is developed by using the frequency-response function, power spectral density function and spatial eigensolution. The root-mean-square velocity response in terms of the one-third octave frequency band is calculated, and then the response reduction capacity through optimizing the complex modulus of the core is analyzed. Numerical results illustrate the influences of the MR elastomer core parameters on the root-mean-square velocity response and the high response reduction capacity of the sandwich beam. The developed analysis method is applicable to sandwich beams with arbitrary cores described by complex shear moduli under arbitrary stochastic excitations described by power spectral density functions

The use of micro-computers in the simulation of ion beam optics

International Nuclear Information System (INIS)

Spaedtke, P.; Ivens, D.

1989-01-01

With computer simulation codes specific problems of the ion beam optics can be studied, which is useful in the design as in optimization of existing systems. Several such codes have been developed, unfortunately requiring substantial computer resources. Recent advances of mini- and micro-computers have now made it possible to develop simulation codes which can be run on these small computers also. In this paper, some of these codes will be presented and their computing time discussed. (author)

PIXE/PIGE characterisation of emeralds using an external micro-beam

International Nuclear Information System (INIS)

Calligaro, T.; Dran, J.-C.; Poirot, J.-P.; Querre, G.; Salomon, J.; Zwaan, J.C.

2000-01-01

A large collection of emeralds of various occurrences has been analysed by PIXE/PIGE in view to establish a compositional database. Major elements (Be, Si, Al) and trace elements (Li, F, Na, Mg, Ca, Rb, Cs and transition metals) are determined using an external 3 MeV proton micro-beam. Elemental micro-mapping permits to select the useful provenance tracers. This database was applied to infer the origin of several ancient emeralds set on historical jewels

In vivo verification of proton beam path by using post-treatment PET/CT imaging.

Science.gov (United States)

Hsi, Wen C; Indelicato, Daniel J; Vargas, Carlos; Duvvuri, Srividya; Li, Zuofeng; Palta, Jatinder

2009-09-01

The purpose of this study is to establish the in vivo verification of proton beam path by using proton-activated positron emission distributions. A total of 50 PET/CT imaging studies were performed on ten prostate cancer patients immediately after daily proton therapy treatment through a single lateral portal. The PET/CT and planning CT were registered by matching the pelvic bones, and the beam path of delivered protons was defined in vivo by the positron emission distribution seen only within the pelvic bones, referred to as the PET-defined beam path. Because of the patient position correction at each fraction, the marker-defined beam path, determined by the centroid of implanted markers seen in the posttreatment (post-Tx) CT, is used for the planned beam path. The angular variation and discordance between the PET- and marker-defined paths were derived to investigate the intrafraction prostate motion. For studies with large discordance, the relative location between the centroid and pelvic bones seen in the post-Tx CT was examined. The PET/CT studies are categorized for distinguishing the prostate motion that occurred before or after beam delivery. The post-PET CT was acquired after PET imaging to investigate prostate motion due to physiological changes during the extended PET acquisition. The less than 2 degrees of angular variation indicates that the patient roll was minimal within the immobilization device. Thirty of the 50 studies with small discordance, referred as good cases, show a consistent alignment between the field edges and the positron emission distributions from the entrance to the distal edge. For those good cases, average displacements are 0.6 and 1.3 mm along the anterior-posterior (D(AP)) and superior-inferior (D(SI)) directions, respectively, with 1.6 mm standard deviations in both directions. For the remaining 20 studies demonstrating a large discordance (more than 6 mm in either D(AP) or D(SI)), 13 studies, referred as motion-after-Tx cases

In vivo verification of proton beam path by using post-treatment PET/CT imaging

Energy Technology Data Exchange (ETDEWEB)

Hsi, Wen C.; Indelicato, Daniel J.; Vargas, Carlos; Duvvuri, Srividya; Li Zuofeng; Palta, Jatinder [Proton Therapy Institute, University of Florida, Jacksonville, Florida 32206 (United States); Boca Radiation Oncology Associates, Boca Raton, Florida 33431 (United States); Proton Therapy Institute, University of Florida, Jacksonville, Florida 32206 (United States); Department of Radiation Oncology, University of Florida, Gainesville, Florida 32610 (United States)

2009-09-15

Purpose: The purpose of this study is to establish the in vivo verification of proton beam path by using proton-activated positron emission distributions. Methods: A total of 50 PET/CT imaging studies were performed on ten prostate cancer patients immediately after daily proton therapy treatment through a single lateral portal. The PET/CT and planning CT were registered by matching the pelvic bones, and the beam path of delivered protons was defined in vivo by the positron emission distribution seen only within the pelvic bones, referred to as the PET-defined beam path. Because of the patient position correction at each fraction, the marker-defined beam path, determined by the centroid of implanted markers seen in the post-treatment (post-Tx) CT, is used for the planned beam path. The angular variation and discordance between the PET- and marker-defined paths were derived to investigate the intrafraction prostate motion. For studies with large discordance, the relative location between the centroid and pelvic bones seen in the post-Tx CT was examined. The PET/CT studies are categorized for distinguishing the prostate motion that occurred before or after beam delivery. The post-PET CT was acquired after PET imaging to investigate prostate motion due to physiological changes during the extended PET acquisition. Results: The less than 2 deg. of angular variation indicates that the patient roll was minimal within the immobilization device. Thirty of the 50 studies with small discordance, referred as good cases, show a consistent alignment between the field edges and the positron emission distributions from the entrance to the distal edge. For those good cases, average displacements are 0.6 and 1.3 mm along the anterior-posterior (D{sub AP}) and superior-inferior (D{sub SI}) directions, respectively, with 1.6 mm standard deviations in both directions. For the remaining 20 studies demonstrating a large discordance (more than 6 mm in either D{sub AP} or D{sub SI}), 13

Cone-beam CT image contrast and attenuation-map linearity improvement (CALI) for brain stereotactic radiosurgery procedures

Science.gov (United States)

Hashemi, Sayed Masoud; Lee, Young; Eriksson, Markus; Nordström, Hâkan; Mainprize, James; Grouza, Vladimir; Huynh, Christopher; Sahgal, Arjun; Song, William Y.; Ruschin, Mark

2017-03-01

A Contrast and Attenuation-map (CT-number) Linearity Improvement (CALI) framework is proposed for cone-beam CT (CBCT) images used for brain stereotactic radiosurgery (SRS). The proposed framework is used together with our high spatial resolution iterative reconstruction algorithm and is tailored for the Leksell Gamma Knife ICON (Elekta, Stockholm, Sweden). The incorporated CBCT system in ICON facilitates frameless SRS planning and treatment delivery. The ICON employs a half-cone geometry to accommodate the existing treatment couch. This geometry increases the amount of artifacts and together with other physical imperfections causes image inhomogeneity and contrast reduction. Our proposed framework includes a preprocessing step, involving a shading and beam-hardening artifact correction, and a post-processing step to correct the dome/capping artifact caused by the spatial variations in x-ray energy generated by bowtie-filter. Our shading correction algorithm relies solely on the acquired projection images (i.e. no prior information required) and utilizes filtered-back-projection (FBP) reconstructed images to generate a segmented bone and soft-tissue map. Ideal projections are estimated from the segmented images and a smoothed version of the difference between the ideal and measured projections is used in correction. The proposed beam-hardening and dome artifact corrections are segmentation free. The CALI was tested on CatPhan, as well as patient images acquired on the ICON system. The resulting clinical brain images show substantial improvements in soft contrast visibility, revealing structures such as ventricles and lesions which were otherwise un-detectable in FBP-reconstructed images. The linearity of the reconstructed attenuation-map was also improved, resulting in more accurate CT#.

Mechanical properties of micro-sized copper bending beams machined by the focused ion beam technique

International Nuclear Information System (INIS)

Motz, C.; Schoeberl, T.; Pippan, R.

2005-01-01

Micro-sized bending beams with thicknesses, t, from 7.5 down to 1.0 μm were fabricated with the focused ion beam technique from a copper single crystal with an {1 1 1} orientation. The beams were loaded with a nano-indenter and the force vs. displacement curves were recorded. A strong size effect was found where the flow stress reaches almost 1 GPa for the thinnest beams. A common strain gradient plasticity approach was used to explain the size effect. However, the strong t -1.14 dependence of the flow stress could not be explained by this model. Additionally, the combination of two other dislocation mechanisms is discussed: the limitation of available dislocation sources and a dislocation pile-up at the beam centre. The contribution of the pile-up stress to the flow stress gives a t -1 dependence, which is in good agreement with the experimental results

Micro-CT based finite element models for elastic properties of glass-ceramic scaffolds.

Science.gov (United States)

Tagliabue, Stefano; Rossi, Erica; Baino, Francesco; Vitale-Brovarone, Chiara; Gastaldi, Dario; Vena, Pasquale

2017-01-01

In this study, the mechanical properties of porous glass-ceramic scaffolds are investigated by means of three-dimensional finite element models based on micro-computed tomography (micro-CT) scan data. In particular, the quantitative relationship between the morpho-architectural features of the obtained scaffolds, such as macroscopic porosity and strut thickness, and elastic properties, is sought. The macroscopic elastic properties of the scaffolds have been obtained through numerical homogenization approaches using the mechanical characteristics of the solid walls of the scaffolds (assessed through nanoindentation) as input parameters for the numerical simulations. Anisotropic mechanical properties of the produced scaffolds have also been investigated by defining a suitable anisotropy index. A comparison with morphological data obtained through the micro-CT scans is also presented. The proposed study shows that the produced glass-ceramic scaffolds exhibited a macroscopic porosity ranging between 29% and 97% which corresponds to an average stiffness ranging between 42.4GPa and 36MPa. A quantitative estimation of the isotropy of the macroscopic elastic properties has been performed showing that the samples with higher solid fractions were those closest to an isotropic material. Copyright © 2016 Elsevier Ltd. All rights reserved.

RHIC beam loss monitor system design

International Nuclear Information System (INIS)

Witkover, R.; Zitvogel, E.; Michnoff, R.

1997-01-01

The Beam Loss Monitor (BLM) System is designed to prevent the quenching of RHIC magnets due to beam loss, provide quantitative loss data, and the loss history in the event of a beam abort. The system uses 400 ion chambers of a modified Tevatron design. To satisfy fast (single turn) and slow (100 msec) loss beam criteria and provide sensitivity for studies measurements, a range of over 8 decades is needed. An RC pre-integrator reduces the dynamic range for a low current amplifier. This is digitized for data logging. The output is also applied to an analog multiplier which compensates the energy dependence, extending the range of the abort comparators. High and low pass filters separate the signal to dual comparators with independent programmable trip levels. Up to 64 channels, on 8 VME boards, are controlled by a micro-controller based VME module, decoupling it from the front-end computer (FEC) for real-time operation. Results with the detectors in the RHIC Sextant Test and the electronics in the AGS-to-RHIC (AtR) transfer line will be presented

Assessment of protocols in cone beam CT with symmetric and asymmetric beam using effective dose and P{sub ka}

Energy Technology Data Exchange (ETDEWEB)

Batista, W. O.; Linhares de O, M. V. [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Barbalho, Salvador, 40301015 Bahia (Brazil); Soares, M. R.; Maia, A. F. [Universidade Federal de Sergipe, Departamento de Fisica, Cidade Universitaria Prof. Jose Aloisio de Campos, Marechal Rondon s/n, Jardim Rosa Elze, 49-100000 Sao Cristovao, Sergipe (Brazil); Caldas, L. V. E., E-mail: wilsonottobatista@gmail.com [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)

2014-08-15

The cone beam CT is an emerging technology in dental radiology with significant differences the point of view of design technology between the various manufacturers on the world market. This study aims to evaluate and compare protocols with similar purposes in a cone beam CT scanner using TLDs and air kerma - area product (P{sub ka}) as kerma index. Measurements were performed on two protocols used to obtain the image the maxilla-mandible in equipment Gendex GXCB 500: Protocol [GX1] extended diameter and asymmetric beam (14 cm x 8.5 cm - maxilla / mandible) and protocol [GX2] symmetrical beam (8.5 cm x 8.5 cm - maxillary / mandible). Was used LiF dosimeters (TLD 100) inserted into a female anthropomorphic phantom manufactured by Radiology Support Devices. For all protocols evaluated the value of P{sub ka} using a meter Diamentor E2 and PTW system Radcal Rapidose. The results obtained for Effective Dose / P{sub ka} these measurements were separated by protocol image. Protocol [GX1]: 44.5 μSv/478 mGy cm{sup 2}; protocol [GX2]: 54.8 μSv/507 mGy cm{sup 2}. These values indicate that the relationship between the diameter of the image acquired in the protocol [GX1] and the diameter of the image in the protocol [GX2] is equal to 1.65, the Effective Dose for the first protocol has lower value at 18%. P{sub ka} values reveal very similar results between the two protocols, although, common sense leads to the interpretation that imaging protocols with field of view (Fov) of large diameters imply high values of effective dose when compared to small diameters. However, in this particular case, this is not true due to the asymmetrical beam technology. Conclude that for the cases where the scanner uses asymmetric beam to obtain images with large diameters that cover the entire face there are advantages from the point of view of reducing the exposure of patients with respect to the use of symmetrical beam and / or to Fov images with a smaller diameter. (Author)

Micro-CT characterization of human trabecular bone in osteogenesis imperfecta

Science.gov (United States)

Jameson, John; Albert, Carolyne; Smith, Peter; Molthen, Robert; Harris, Gerald

2011-03-01

Osteogenesis imperfecta (OI) is a genetic syndrome affecting collagen synthesis and assembly. Its symptoms vary widely but commonly include bone fragility, reduced stature, and bone deformity. Because of the small size and paucity of human specimens, there is a lack of biomechanical data for OI bone. Most literature has focused on histomorphometric analyses, which rely on assumptions to extrapolate 3-D properties. In this study, a micro-computed tomography (μCT) system was used to directly measure structural and mineral properties in pediatric OI bone collected during routine surgical procedures. Surface renderings suggested a poorly organized, plate-like orientation. Patients with a history of bone-augmenting drugs exhibited increased bone volume fraction (BV/TV), trabecular number (Tb.N), and connectivity density (Eu.Conn.D). The latter two parameters appeared to be related to OI severity. Structural results were consistently higher than those reported in a previous histomorphometric study, but these differences can be attributed to factors such as specimen collection site, drug therapy, and assumptions associated with histomorphometry. Mineral testing revealed strong correlations with several structural parameters, highlighting the importance of a dual approach in trabecular bone testing. This study reports some of the first quantitative μCT data of human OI bone, and it suggests compelling possibilities for the future of OI bone assessment.

Cone beam computed tomography image guidance system for a dedicated intracranial radiosurgery treatment unit.

Science.gov (United States)

Ruschin, Mark; Komljenovic, Philip T; Ansell, Steve; Ménard, Cynthia; Bootsma, Gregory; Cho, Young-Bin; Chung, Caroline; Jaffray, David

2013-01-01

Image guidance has improved the precision of fractionated radiation treatment delivery on linear accelerators. Precise radiation delivery is particularly critical when high doses are delivered to complex shapes with steep dose gradients near critical structures, as is the case for intracranial radiosurgery. To reduce potential geometric uncertainties, a cone beam computed tomography (CT) image guidance system was developed in-house to generate high-resolution images of the head at the time of treatment, using a dedicated radiosurgery unit. The performance and initial clinical use of this imaging system are described. A kilovoltage cone beam CT system was integrated with a Leksell Gamma Knife Perfexion radiosurgery unit. The X-ray tube and flat-panel detector are mounted on a translational arm, which is parked above the treatment unit when not in use. Upon descent, a rotational axis provides 210° of rotation for cone beam CT scans. Mechanical integrity of the system was evaluated over a 6-month period. Subsequent clinical commissioning included end-to-end testing of targeting performance and subjective image quality performance in phantoms. The system has been used to image 2 patients, 1 of whom received single-fraction radiosurgery and 1 who received 3 fractions, using a relocatable head frame. Images of phantoms demonstrated soft tissue contrast visibility and submillimeter spatial resolution. A contrast difference of 35 HU was easily detected at a calibration dose of 1.2 cGy (center of head phantom). The shape of the mechanical flex vs scan angle was highly reproducible and exhibited cone beam CT image guidance system was successfully adapted to a radiosurgery unit. The system is capable of producing high-resolution images of bone and soft tissue. The system is in clinical use and provides excellent image guidance without invasive frames. Copyright © 2013 Elsevier Inc. All rights reserved.

Estimation of mouse organ locations through registration of a statistical mouse atlas with micro-CT images.

Science.gov (United States)

Wang, Hongkai; Stout, David B; Chatziioannou, Arion F

2012-01-01

Micro-CT is widely used in preclinical studies of small animals. Due to the low soft-tissue contrast in typical studies, segmentation of soft tissue organs from noncontrast enhanced micro-CT images is a challenging problem. Here, we propose an atlas-based approach for estimating the major organs in mouse micro-CT images. A statistical atlas of major trunk organs was constructed based on 45 training subjects. The statistical shape model technique was used to include inter-subject anatomical variations. The shape correlations between different organs were described using a conditional Gaussian model. For registration, first the high-contrast organs in micro-CT images were registered by fitting the statistical shape model, while the low-contrast organs were subsequently estimated from the high-contrast organs using the conditional Gaussian model. The registration accuracy was validated based on 23 noncontrast-enhanced and 45 contrast-enhanced micro-CT images. Three different accuracy metrics (Dice coefficient, organ volume recovery coefficient, and surface distance) were used for evaluation. The Dice coefficients vary from 0.45 ± 0.18 for the spleen to 0.90 ± 0.02 for the lungs, the volume recovery coefficients vary from 0.96 ± 0.10 for the liver to 1.30 ± 0.75 for the spleen, the surface distances vary from 0.18 ± 0.01 mm for the lungs to 0.72 ± 0.42 mm for the spleen. The registration accuracy of the statistical atlas was compared with two publicly available single-subject mouse atlases, i.e., the MOBY phantom and the DIGIMOUSE atlas, and the results proved that the statistical atlas is more accurate than the single atlases. To evaluate the influence of the training subject size, different numbers of training subjects were used for atlas construction and registration. The results showed an improvement of the registration accuracy when more training subjects were used for the atlas construction. The statistical atlas-based registration was also compared with

In situ micro-focused X-ray beam characterization with a lensless camera using a hybrid pixel detector

International Nuclear Information System (INIS)

Kachatkou, Anton; Marchal, Julien; Silfhout, Roelof van

2014-01-01

Position and size measurements of a micro-focused X-ray beam, using an X-ray beam imaging device based on a lensless camera that collects radiation scattered from a thin foil placed in the path of the beam at an oblique angle, are reported. Results of studies on micro-focused X-ray beam diagnostics using an X-ray beam imaging (XBI) instrument based on the idea of recording radiation scattered from a thin foil of a low-Z material with a lensless camera are reported. The XBI instrument captures magnified images of the scattering region within the foil as illuminated by the incident beam. These images contain information about beam size, beam position and beam intensity that is extracted during dedicated signal processing steps. In this work the use of the device with beams for which the beam size is significantly smaller than that of a single detector pixel is explored. The performance of the XBI device equipped with a state-of-the-art hybrid pixel X-ray imaging sensor is analysed. Compared with traditional methods such as slit edge or wire scanners, the XBI micro-focused beam characterization is significantly faster and does not interfere with on-going experiments. The challenges associated with measuring micrometre-sized beams are described and ways of optimizing the resolution of beam position and size measurements of the XBI instrument are discussed

Evaluation of a method for correction of scatter radiation in thorax cone beam CT

International Nuclear Information System (INIS)

Rinkel, J.; Dinten, J.M.; Esteve, F.

2004-01-01

Purpose: Cone beam CT (CBCT) enables three-dimensional imaging with isotropic resolution. X-ray scatter estimation is a big challenge for quantitative CBCT imaging of thorax: scatter level is significantly higher on cone beam systems compared to collimated fan beam systems. The effects of this scattered radiation are cupping artefacts, streaks, and quantification inaccuracies. The beam stops conventional scatter estimation approach can be used for CBCT but leads to a significant increase in terms of dose and acquisition time. At CEA-LETI has been developed an original scatter management process without supplementary acquisition. Methods and Materials: This Analytical Plus Indexing-based method (API) of scatter correction in CBCT is based on scatter calibration through offline acquisitions with beam stops on lucite plates, combined to an analytical transformation issued from physical equations. This approach has been applied with success in bone densitometry and mammography. To evaluate this method in CBCT, acquisitions from a thorax phantom with and without beam stops have been performed. To compare different scatter correction approaches, Feldkamp algorithm has been applied on rough data corrected from scatter by API and by beam stops approaches. Results: The API method provides results in good agreement with the beam stops array approach, suppressing cupping artefact. Otherwise influence of the scatter correction method on the noise in the reconstructed images has been evaluated. Conclusion: The results indicate that the API method is effective for quantitative CBCT imaging of thorax. Compared to a beam stops array method it needs a lower x-ray dose and shortens acquisition time. (authors)

SU-E-J-47: Comparison of Online Image Registrations of Varian TrueBeam Cone-Beam CT and BrainLab ExacTrac Imaging Systems

International Nuclear Information System (INIS)

Li, J; Shi, W; Andrews, D; Werner-Wasik, M; Yu, Y; Liu, H

2015-01-01

Purpose To compare online image registrations of TrueBeam cone-beam CT (CBCT) and BrainLab ExacTrac imaging systems. Methods Tests were performed on a Varian TrueBeam STx linear accelerator (Version 2.0), which is integrated with a BrainLab ExacTrac imaging system (Version 6.0.5). The study was focused on comparing the online image registrations for translational shifts. A Rando head phantom was placed on treatment couch and immobilized with a BrainLab mask. The phantom was shifted by moving the couch translationally for 8 mm with a step size of 1 mm, in vertical, longitudinal, and lateral directions, respectively. At each location, the phantom was imaged with CBCT and ExacTrac x-ray. CBCT images were registered with TrueBeam and ExacTrac online registration algorithms, respectively. And ExacTrac x-ray image registrations were performed. Shifts calculated from different registrations were compared with nominal couch shifts. Results The averages and ranges of absolute differences between couch shifts and calculated phantom shifts obtained from ExacTrac x-ray registration, ExacTrac CBCT registration with default window, ExaxTrac CBCT registration with adjusted window (bone), Truebeam CBCT registration with bone window, and Truebeam CBCT registration with soft tissue window, were: 0.07 (0.02–0.14), 0.14 (0.01–0.35), 0.12 (0.02–0.28), 0.09 (0–0.20), and 0.06 (0–0.10) mm, in vertical direction; 0.06 (0.01–0.12), 0.27 (0.07–0.57), 0.23 (0.02–0.48), 0.04 (0–0.10), and 0.08 (0– 0.20) mm, in longitudinal direction; 0.05 (0.01–0.21), 0.35 (0.14–0.80), 0.25 (0.01–0.56), 0.19 (0–0.40), and 0.20 (0–0.40) mm, in lateral direction. Conclusion The shifts calculated from ExacTrac x-ray and TrueBeam CBCT registrations were close to each other (the differences between were less than 0.40 mm in any direction), and had better agreements with couch shifts than those from ExacTrac CBCT registrations. There were no significant differences between TrueBeam

Trabecular bone structural parameters evaluated using dental cone-beam computed tomography: cellular synthetic bones.

Science.gov (United States)

Ho, Jung-Ting; Wu, Jay; Huang, Heng-Li; Chen, Michael Y c; Fuh, Lih-Jyh; Hsu, Jui-Ting

2013-11-09

This study compared the adequacy of dental cone beam computed tomography (CBCT) and micro computed tomography (micro-CT) in evaluating the structural parameters of trabecular bones. The cellular synthetic bones in 4 density groups (Groups 1-4: 0.12, 0.16, 0.20, and 0.32 g/cm3) were used in this study. Each group comprised 8 experimental specimens that were approximately 1 cm3. Dental CBCT and micro-CT scans were conducted on each specimen to obtain independent measurements of the following 4 trabecular bone structural parameters: bone volume fraction (BV/TV), specific bone surface (BS/BV), trabecular thickness (Tb.Th.), and trabecular separation (Tb.Sp.). Wilcoxon signed ranks tests were used to compare the measurement variations between the dental CBCT and micro-CT scans. A Spearman analysis was conducted to calculate the correlation coefficients (r) of the dental CBCT and micro-CT measurements. Of the 4 groups, the BV/TV and Tb.Th. measured using dental CBCT were larger compared with those measured using micro-CT. By contrast, the BS/BV measured using dental CBCT was significantly less compared with those measured using micro-CT. Furthermore, in the low-density groups (Groups 1 and 2), the Tb.Sp. measured using dental CBCT was smaller compared with those measured using micro-CT. However, the Tb.Sp. measured using dental CBCT was slightly larger in the high-density groups (Groups 3 and 4) than it was in the low density groups. The correlation coefficients between the BV/TV, BS/BV, Tb.Th., and Tb.Sp. values measured using dental CBCT and micro-CT were 0.9296 (p < .001), 0.8061 (p < .001), 0.9390 (p < .001), and 0.9583 (p < .001), respectively. Although the dental CBCT and micro-CT approaches exhibited high correlations, the absolute values of BV/TV, BS/BV, Tb.Th., Tb.Sp. differed significantly between these measurements. Additional studies must be conducted to evaluate using dental CBCT in clinical practice.

Petrographic characterization to build an accurate rock model using micro-CT: Case study on low-permeable to tight turbidite sandstone from Eocene Shahejie Formation.

Science.gov (United States)

Munawar, Muhammad Jawad; Lin, Chengyan; Cnudde, Veerle; Bultreys, Tom; Dong, Chunmei; Zhang, Xianguo; De Boever, Wesley; Zahid, Muhammad Aleem; Wu, Yuqi

2018-03-26

Pore scale flow simulations heavily depend on petrographic characterizing and modeling of reservoir rocks. Mineral phase segmentation and pore network modeling are crucial stages in micro-CT based rock modeling. The success of the pore network model (PNM) to predict petrophysical properties relies on image segmentation, image resolution and most importantly nature of rock (homogenous, complex or microporous). The pore network modeling has experienced extensive research and development during last decade, however the application of these models to a variety of naturally heterogenous reservoir rock is still a challenge. In this paper, four samples from a low permeable to tight sandstone reservoir were used to characterize their petrographic and petrophysical properties using high-resolution micro-CT imaging. The phase segmentation analysis from micro-CT images shows that 5-6% microporous regions are present in kaolinite rich sandstone (E3 and E4), while 1.7-1.8% are present in illite rich sandstone (E1 and E2). The pore system percolates without micropores in E1 and E2 while it does not percolate without micropores in E3 and E4. In E1 and E2, total MICP porosity is equal to the volume percent of macrospores determined from micro-CT images, which indicate that the macropores are well connected and microspores do not play any role in non-wetting fluid (mercury) displacement process. Whereas in E3 and E4 sandstones, the volume percent of micropores is far less (almost 50%) than the total MICP porosity which means that almost half of the pore space was not detected by the micro-CT scan. PNM behaved well in E1 and E2 where better agreement exists in PNM and MICP measurements. While E3 and E4 exhibit multiscale pore space which cannot be addressed with single scale PNM method, a multiscale approach is needed to characterize such complex rocks. This study provides helpful insights towards the application of existing micro-CT based petrographic characterization methodology

Investigating the effect of longitudinal micro-CT imaging on tumour growth in mice

Energy Technology Data Exchange (ETDEWEB)

Foster, W Kyle; Ford, Nancy L, E-mail: nlford@ryerson.ca [Department of Physics, Ryerson University, Toronto, Ontario M5B 2K3 (Canada)

2011-01-21

The aim of this study is to determine the impact of longitudinal micro-CT imaging on the growth of B16F1 tumours in C57BL/6 mice. Sixty mice received 2 x 10{sup 5} B16F1 cells subcutaneously in the hind flank and were divided into control (no scan), 'low-dose' (80 kVp, 70 mA, 8 s, 0.07 Gy), 'medium-dose' (80 kVp, 50 mA, 30 s, 0.18 Gy) and 'high-dose' (80 kVp, 50 mA, 50 s, 0.30 Gy) groups. All imaging was performed on a fast volumetric micro-CT scanner (GE Locus Ultra, London, Canada). Each mouse was imaged on days 4, 8, 12 and 16. After the final imaging session, each tumour was excised, weighed on an electronic balance, imaged to obtain the final tumour volume and processed for histology. Final tumour volume was used to evaluate the impact of longitudinal micro-CT imaging on the tumour growth. An ANOVA indicated no statistically significant difference in tumour volume (p = 0.331, {alpha} = {beta} = 0.1) when discriminating against a treatment-sized effect. Histological samples revealed no observable differences in apoptosis or cell proliferation. We conclude that four imaging sessions, using standard protocols, over the course of 16 days did not cause significant changes in final tumour volume for B16F1 tumours in female C57BL/6 mice (ANOVA, {alpha} = {beta} = 0.1, p = 0.331).

Fully automated segmentation of callus by micro-CT compared to biomechanics.

Science.gov (United States)

Bissinger, Oliver; Götz, Carolin; Wolff, Klaus-Dietrich; Hapfelmeier, Alexander; Prodinger, Peter Michael; Tischer, Thomas

2017-07-11

A high percentage of closed femur fractures have slight comminution. Using micro-CT (μCT), multiple fragment segmentation is much more difficult than segmentation of unfractured or osteotomied bone. Manual or semi-automated segmentation has been performed to date. However, such segmentation is extremely laborious, time-consuming and error-prone. Our aim was to therefore apply a fully automated segmentation algorithm to determine μCT parameters and examine their association with biomechanics. The femura of 64 rats taken after randomised inhibitory or neutral medication, in terms of the effect on fracture healing, and controls were closed fractured after a Kirschner wire was inserted. After 21 days, μCT and biomechanical parameters were determined by a fully automated method and correlated (Pearson's correlation). The fully automated segmentation algorithm automatically detected bone and simultaneously separated cortical bone from callus without requiring ROI selection for each single bony structure. We found an association of structural callus parameters obtained by μCT to the biomechanical properties. However, results were only explicable by additionally considering the callus location. A large number of slightly comminuted fractures in combination with therapies that influence the callus qualitatively and/or quantitatively considerably affects the association between μCT and biomechanics. In the future, contrast-enhanced μCT imaging of the callus cartilage might provide more information to improve the non-destructive and non-invasive prediction of callus mechanical properties. As studies evaluating such important drugs increase, fully automated segmentation appears to be clinically important.

Neutron CT with a multi-detector system leading to drastical reduction of the measuring time

International Nuclear Information System (INIS)

Hehn, G.; Pfister, G.; Schatz, A.; Goebel, J.; Kofler, R.

1993-09-01

By means of numerical simulation methods and their verification with measurements it could be shown that such a detector system can be realized for a line beam and 1-2 detectors per cm. With the maximum available beam width of the fast neutron field at the FRM approximately 20 detectors can be used leading to a reduction of the measuring time to 0,5 - 1 hour. A multi detector system for a line beam of thermal neutrons was constructed, tested and used for CT-measurements. This detector system for the measurement of thinner layers with better spatial resolution could be realized. The electronic discrimination between neutrons and gamma rays has been improved. This discrimination was used in all CT-measurements to get transmission values of both kinds of radiation and to reconstruct to complementary CT-images. The use of a polyenergetic radiation causes spectral shifts in the transmission spectrum leading to artifacts in the reconstructed CT-image. The transmission values must be spectral corrected before image reconstruction, because the image artifacts complicate the image evaluation or make it impossible. A new energy selective procedure for the online spectral correction was developed. This method is based on the concept to measure additionally to the integral transmission value his pulse height spectrum and to do the correction depending on the changes in this pulse height spectrum. (orig./HP) [de

A combination-weighted Feldkamp-based reconstruction algorithm for cone-beam CT

International Nuclear Information System (INIS)

Mori, Shinichiro; Endo, Masahiro; Komatsu, Shuhei; Kandatsu, Susumu; Yashiro, Tomoyasu; Baba, Masayuki

2006-01-01

The combination-weighted Feldkamp algorithm (CW-FDK) was developed and tested in a phantom in order to reduce cone-beam artefacts and enhance cranio-caudal reconstruction coverage in an attempt to improve image quality when utilizing cone-beam computed tomography (CBCT). Using a 256-slice cone-beam CT (256CBCT), image quality (CT-number uniformity and geometrical accuracy) was quantitatively evaluated in phantom and clinical studies, and the results were compared to those obtained with the original Feldkamp algorithm. A clinical study was done in lung cancer patients under breath holding and free breathing. Image quality for the original Feldkamp algorithm is degraded at the edge of the scan region due to the missing volume, commensurate with the cranio-caudal distance between the reconstruction and central planes. The CW-FDK extended the reconstruction coverage to equal the scan coverage and improved reconstruction accuracy, unaffected by the cranio-caudal distance. The extended reconstruction coverage with good image quality provided by the CW-FDK will be clinically investigated for improving diagnostic and radiotherapy applications. In addition, this algorithm can also be adapted for use in relatively wide cone-angle CBCT such as with a flat-panel detector CBCT

Compact high-efficiency vortex beam emitter based on a silicon photonics micro-ring

DEFF Research Database (Denmark)

Li, Shimao; Ding, Yunhong; Guan, Xiaowei

2018-01-01

Photonic integrated devices that emit vortex beam carrying orbital angular momentum are becoming key components for multiple applications. Here we propose and demonstrate a high-efficiency vortex beam emitter based on a silicon micro-ring resonator integrated with a metal mirror. Such a compact...

Manufacturing of Three-dimensional Micro Structure Using Proton Beam

Energy Technology Data Exchange (ETDEWEB)

Lee, Suonggyu; Kwon, Wontae [Seoul University, Seoul (Korea, Republic of)

2015-04-15

The diameter of a proton beam emanating from the MC-50 cyclotron is about 2?3 mm with Gaussian distribution. This widely irradiated proton beam is not suitable for semiconductor etching, precise positioning, and micromachining, which require a small spot. In this study, a beam cutting method using a microhole is proposed as an economical alternative. We produced a microhole with aspect ratio, average diameter, and thickness of 428, 21 μm, and 9 mm, respectively, for cutting the proton beam. By using this high-aspect-ratio microhole, we conducted machinability tests on microstructures with sizes of tens of μm. Additionally, the results of simulation using GEANT4 and those of the actual experiment were compared and analyzed. The outcome confirmed the possibility of implementing a micro process technology for the fabrication of three-dimensional microstructures of 20 micron units using the MC-50 cyclotron with the microhole.

Neutral particle beam distributed data acquisition system

International Nuclear Information System (INIS)

Daly, R.T.; Kraimer, M.R.; Novick, A.H.

1987-01-01

A distributed data acquisition system has been designed to support experiments at the Argonne Neutral Particle Beam Accelerator. The system uses a host VAXstation II/GPX computer acting as an experimenter's station linked via Ethernet with multiple MicroVAX IIs and rtVAXs dedicated to acquiring data and controlling hardware at remote sites. This paper describes the hardware design of the system, the applications support software on the host and target computers, and the real-time performance

Micro-CT evaluation of microleakage under orthodontic ceramic brackets bonded with different bonding techniques and adhesives.

Science.gov (United States)

Öztürk, Fırat; Ersöz, Mustafa; Öztürk, Seyit Ahmet; Hatunoğlu, Erdem; Malkoç, Sıddık

2016-04-01

The aim of this study was to evaluate microleakage under orthodontic ceramic brackets bonded with direct and different indirect bonding techniques and adhesives using micro-computed tomography. A total of 30 human maxillary premolars were randomly separated into five groups with six teeth in each group. In group I, teeth were bonded directly with Transbond XT (3M Unitek). In group II, group III, group IV, and group V, teeth were bonded through an indirect technique with Custom I.Q. (Reliance Orthodontic Products), Sondhi Rapid-Set (3M Unitek), RMbond (RMO), and Transbond IDB (3M Unitek), respectively, following the manufacturer's instructions. Micro-CT system model 1172 of Skyscan (Kontich, Belgium) was used to scan all samples. NRecon (Skyscan) version 1.6, CT-Analyser V.1.11 (Skyscan), and TView (SkyScan, Bvba) software programs were used for microleakage evaluation. Microleakage values between the test groups were assessed using the Kruskal-Wallis test, while the Wilcoxon signed rank test was used for within-group comparisons. The level of significance was set at P Kruskal-Wallis analysis of variance test, there were no significant differences among the tested groups, with regard to volume and percentage (microleakage/region of interest × 100) of microleakage values (P test showed that coronal microleakage volume and percentage values significantly differed for RMbond and Transbond IDB groups. In the study, only ceramic brackets were used and microleakage into mini gaps did not show up on the micro-CT image because 50% silver nitrate solution could not penetrate into mini gaps which are smaller than silver nitrate particles. Use of direct and indirect bonding techniques with different adhesives did not significantly affect the amount of microleakage. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Study of the electroforming technology for high-aspect ratio micro structure which was machined by using proton beam writing

International Nuclear Information System (INIS)

Okamoto, N.

2009-01-01

In this study, we develop the formation process of Ni electrodeposited micro patterns, which is used for MEMS devices or nano-imprinting. The purpose of my study is creating the new process of fabricating 3-D complicated micro-pattern or micro-devices using electroforming and proton beam writing. In general, 'Through mask process' (like a LIGA process) is usually used to fabricate Ni electrodeposited micro patterns for making MEMS devices or microfabricated-molds. The strong point of 'Through mask process' is the simple shape of the electrode. It makes the deposition process easy, because the electrodeposited films just glow up from the bottom to top surface of the mold. And the shape of the electrodeposited films is the same as the electrode pattern from the bottom to top, like a simple pillar shape. However, this process also has some problems. In case of using 'Through mask process', it is difficult to fabricate the complicated 3-D shaped structures, which are bended, parted or severed at some part of the structure between the bottom and top, like a device with a micro sensor or micro total analysis system. In order to overcome these limitations, we try to fabricate Ni electrodeposited micro patterns using 'the Damascene process' and proton beam writing. (author)

SU-F-T-215: An Investigation Of Multi-Scanner CT Hounsfield Unit Calibration for Pencil Beam Scanning Proton Therapy Using 3D Gamma Analysis

International Nuclear Information System (INIS)

Zhang, J; Li, X; Liu, G; Liu, Q; Liang, J; Ding, X

2016-01-01

Purpose: We compare and investigate the dosimetric impacts on pencil beam scanning (PBS) proton treatment plans generated with CT calibration curves from four different CT scanners and one averaged ‘global’ CT calibration curve. Methods: The four CT scanners are located at three different hospital locations within the same health system. CT density calibration curves were collected from these scanners using the same CT calibration phantom and acquisition parameters. Mass density to HU value tables were then commissioned in a commercial treatment planning system. Five disease sites were chosen for dosimetric comparisons at brain, lung, head and neck, adrenal, and prostate. Three types of PBS plans were generated at each treatment site using SFUD, IMPT, and robustness optimized IMPT techniques. 3D dose differences were investigated using 3D Gamma analysis. Results: The CT calibration curves for all four scanners display very similar shapes. Large HU differences were observed at both the high HU and low HU regions of the curves. Large dose differences were generally observed at the distal edges of the beams and they are beam angle dependent. Out of the five treatment sites, lung plans exhibits the most overall range uncertainties and prostate plans have the greatest dose discrepancy. There are no significant differences between the SFUD, IMPT, and the RO-IMPT methods. 3D gamma analysis with 3%, 3 mm criteria showed all plans with greater than 95% passing rate. Two of the scanners with close HU values have negligible dose difference except for lung. Conclusion: Our study shows that there are more than 5% dosimetric differences between different CT calibration curves. PBS treatment plans generated with SFUD, IMPT, and the robustness optimized IMPT has similar sensitivity to the CT density uncertainty. More patient data and tighter gamma criteria based on structure location and size will be used for further investigation.

Scanning ion micro-beam techniques for measuring diffusion in heterogeneous materials

International Nuclear Information System (INIS)

Jenneson, P.M.; Clough, A.S.

1998-01-01

A raster scanning MeV micro-beam of 1 H + or 3 He + ions was used to study the diffusion of small molecules in heterogeneous materials. The location of elemental contaminants (heavier than Lithium) in polymer insulated cables was studied with 1 H micro-Particle Induced X-ray Emission (μPIXE). Concentration profiles of a deuterated molecule in a hair fibre were determined with 3 He micro-Nuclear Reaction Analysis (μNRA). Chlorine and heavy water (D 2 0) diffusion into cement pastes were profiled using a combination of 3 He μPIXE and μNRA. (authors)

Evaluation of occurring complications after flow diverter treatment of elastase-induced aneurysm in rabbits using micro-CT and MRI at 9.4 T

Energy Technology Data Exchange (ETDEWEB)

Simgen, Andreas; Ley, Desiree; Muehl-Benninghaus, Ruben; Koerner, Heiko; Reith, Wolfgang; Yilmaz, Umut [Saarland University Hospital, Department of Neuroradiology, Homburg, Saar (Germany); Roth, Christian [Clinic Bremen-Mitte, Department of Neuroradiology, Bremen (Germany); Cattaneo, Giorgio Franco Maria [Acandis GmbH, Pforzheim (Germany); Mueller, Andreas [Saarland University Hospital, Department of Experimental Surgery, Homburg, Saar (Germany); Kim, Yoo-Jin [Saarland University Hospital, Department of Pathology, Homburg, Saar (Germany); Scheller, Bruno [Saarland University Hospital, Department of Cardiology, Homburg, Saar (Germany)

2016-10-15

Flow diverters are increasingly being used to treat intracranial aneurysms. This study evaluates occurring complications of flow-diverting devices in the treatment of experimental aneurysms, involving the use of micro-CT and small animal MRI at 9.4 T, in correlation to angiographic and histological findings. We previously published two preclinical studies, in which we assessed two different flow diverters in the treatment of elastase-induced aneurysms. Devices have been implanted across the aneurysm neck as well as in the abdominal aorta. From these studies, a total of 65 devices (prototype FD (n = 30) and Derivo embolization device (n = 35)) additionally underwent micro-CT and MRI after angiographic follow-up and before being histologically examined. The different architectures of both devices were precisely comparable due to high-resolution micro-CT imaging. Micro-CT revealed wire fractures in nine cases (30 %) only with the prototype FD. In three cases (10 %), severe wire fractures correlated with an in-stent stenosis due to intimal hyperplasia. Other complications, like distal stent occlusions and post-stent stenosis, were seen in both groups and verified with both imaging techniques. Osseous metaplasia were correlated to calcifications seen with micro-CT. MRI enabled visualization of the position of the implanted devices relative to the aneurysm and revealed incomplete aneurysm neck coverage with the prototype FD in two cases (6.7 %). Micro-CT and 9.4-T MRI are valid to discover and understand occurring complications of flow diverters in the preclinical phase and can serve as evaluation tools to minimize complication rates of endovascular devices in the future. (orig.)

Micro X-ray CT imaging of pore-scale changes in unconsolidated sediment under confining pressure

Science.gov (United States)

Schindler, M.; Prasad, M.

2017-12-01

Micro X-ray computed tomography was used to image confining-pressure induced changes in a dry, unconsolidated quartz sand pack while simultaneously recording ultrasonic P-wave velocities. The experiments were performed under in-situ pressure of up to 4000 psi. The majority of digital rock physics studies rely on micro CT images obtained under ambient pressure and temperature conditions although effective rock properties strongly depend on in situ conditions. Goal of this work is to be able to obtain micro CT images of rock samples while pore and confining pressure is applied. Simultaneously we recorded ultrasonic P-wave velocities. The combination of imaging and velocity measurements provides insight in pore-scale changes in the rock and their influence on elastic properties. We visually observed a reduction in porosity by more than a third of the initial value as well as extensive grain damage, changes in pore and grain size distribution and an increase in contact number and contact radius with increasing confining pressure. An increase in measured ultrasonic P-wave velocities with increasing pressure was observed. We used porosity, contact number and contact radius obtained from micro CT images to model P-wave velocity with the contact-radius model by Bachrach et al. (1998). Our observations showed that the frame of unconsolidated sediments is significantly altered starting at pressures of only 1000 psi. This finding indicates that common assumptions in rock physics models (the solid frame remains unchanged) are violated for unconsolidated sediments. The effects on the solid frame should be taken into account when modeling the pressure dependence of elastic rock properties.

Improved automated production of 18F-FMISO and its tumor hypoxia imaging by Micro-PET/CT

International Nuclear Information System (INIS)

Wang Mingwei; Zhang Yongping; Zheng Yujia; Bao Xiao; Zheng Yingjian

2013-01-01

Background: 1-H-1-(3-[ 18 F]fluoro-2-hydroxypropyl)-2-nitroimidazole ( 18 F-FMISO) is a specific molecular imaging probe for tumor hypoxia imaging, and its PET/CT imaging has an important clinical value for planning cancer radiotherapy target volume. Purpose: This study aimed to develop an improved, automated production of 18 F-FMISO and to perform Micro-PET/CT imaging of tumor hypoxia. Methods: Based on the labeling precursor NITTP and a simple 'one-pot' method, an upgraded Explora GN module together with Explora LC was adopted to run radiofluorination (NITTP (10 mg), MeCN (1.0 mL), 120℃, 5.0 min), hydrolysis (HCI (1.0 mol/L, 1.0 mL), 130℃, 8.0 min) and high performance liquid chromatography (HPLC) purification to produce 18 F-FMISO automatically. Moreover, Radio-HPLC and Radio-TLC were applied for the quality control, and Micro-PET/CT scanner for hypoxia imaging of SW1990 pancreatic tumor-bearing mice. Results: As results, 18 F-FMISO was obtained with the synthesis time for about 65 min, the radiochemical yield of (30±5.0)% (no decay corrected, n=20), the radiochemical purity of above 99%, the specific activity of (2.04±0.17)x10 11 Bq·μmol -1 , plus with the enhanced chemical purity. Moreover, MicroPET/CT imaging showed that 18 F-FMISO presented whole-body distribution in SW1990 tumor-bearing mice, and the optimized time point for tumor hypoxia imaging was 3 h post injection with the uptake ratios of tumor-to-muscle of 3.00±0.08. Conclusion: In sum, we developed an improved, automated production of 18 F-FMISO with high performance liquid chromatography purification, high radiochemical yield, high specific activity and high reliability , and also verified its MicroPET/CT imaging of tumor hypoxia for providing experimental reference data. (authors)

Development of a Method to Assess the Precision Of the z-axis X-ray Beam Collimation in a CT Scanner

Science.gov (United States)

Kim, Yon-Min

2018-05-01

Generally X-ray equipment specifies the beam collimator for the accuracy measurement as a quality control item, but the computed tomography (CT) scanner with high dose has no collimator accuracy measurement item. If the radiation dose is to be reduced, an important step is to check if the beam precisely collimates at the body part for CT scan. However, few ways are available to assess how precisely the X-ray beam is collimated. In this regard, this paper provides a way to assess the precision of z-axis X-ray beam collimation in a CT scanner. After the image plate cassette had been exposed to the X-ray beam, the exposed width was automatically detected by using a computer program developed by the research team to calculate the difference between the exposed width and the imaged width (at isocenter). The result for the precision of z-axis X-ray beam collimation showed that the exposed width was 3.8 mm and the overexposure was high at 304% when a narrow beam of a 1.25 mm imaged width was used. In this study, the precision of the beam collimation of the CT scanner, which is frequently used for medical services, was measured in a convenient way by using the image plate (IP) cassette.

Characterization of triboluminescent enhanced discontinuous glass–fiber composite beams for micro-damage detection and fracture assessment

Energy Technology Data Exchange (ETDEWEB)

Dickens, Tarik, E-mail: dickens@eng.fsu.edu [Department of Industrial & Manufacturing Engineering, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Nanotechnology Patronas Group Inc., Tallahassee, FL 32311 (United States); Armbrister, Chelsea [Department of Industrial & Manufacturing Engineering, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Olawale, David [Department of Industrial & Manufacturing Engineering, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Nanotechnology Patronas Group Inc., Tallahassee, FL 32311 (United States); Okoli, Okenwa [Department of Industrial & Manufacturing Engineering, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States)

2015-07-15

This work reports the micro-emissions of triboluminescent (TL) concentrated composites and their evaluation at the onset of damage and crack propagation. Unreinforced vinyl ester resin and discontinuous glass–fiber reinforced non-prismatic beams were fabricated incorporating 10 wt% concentration of a highly triboluminescent material (ZnS:Mn). Triboluminescent observations were seen in both two- and three-phase composite systems throughout the failure loading-cycle. Results indicate emissions occur at various intensities corresponding to initial notch-length and imminent micro-matrix fracture. The fracturing or deformation energy was estimated by an experimental method of the J-integral analysis [1], where a lower threshold for excitation was found to be approximately less than 0.5 J m{sup −2}, below its respective critical composite fracture energy (~3 and 7 J m{sup −2}). Initiation of micro-cracks was observed for reinforced samples and were subjected to three-point bend tests in lieu of the multiple signatures of the transient signal response. - Highlights: • We examined triboluminescence of reinforced and unreinforced beams. • The addition of J-integral fracture analysis indicates low energy excitation. • Excitation is related to matrix fracture in unreinforced samples. • Excitation is related to micro-matrix fracture and potential fiber failure.

[Ex vivo microCT analysis of possible microfractures of the femoral head during implantation of a cementless hip resurfacing femoral component].

Science.gov (United States)

Lerch, M; Olender, G; von der Höh, N; Thorey, F; von Lewinski, G; Meyer-Lindenberg, A; Windhagen, H; Hurschler, C

2009-01-01

Microfractures of the femoral head during implantation of the femoral components are suspected to be a cause of fractures at the implant/neck junction which represent a common failure mode in hip resurfacing arthroplasty. Callus formation observed in femoral head retrievals suggests the occurrence of microfractures inside the femoral head, which might be inadvertently caused by the surgeon during implantation. The aim of this biomechanical study was to analyse whether or not the implantation of a cementless femoral component hip resurfacing system causes microfractures in the femoral head. After the preparation of 20 paired human cadaveric femoral heads, the cementless femoral component ESKA Typ BS (ESKA Implants GmbH & Co., Lübeck) was implanted on 9 specimens with an impaction device that generates 4.5 kN impaction force. On 9 specimens the femoral component was implanted by hand. One head was used as a fracture model, 1 specimen served as control without manipulation. The femoral component used for impaction was equipped with hinges to enable its removal without further interfering with the bone stock. Specimens were scanned with a microCT device before and after impaction and the microCT datasets before and after impaction were compared to identify possible microfractures. Twenty strikes per hand or with the impaction device provided sufficient implant seating. Neither the macroscopic examination nor the 2-dimensional microCT analysis revealed any fractures of the femoral heads after impaction. At least macroscopically and in the 2-dimensional microCT analysis, implantation of the cementless hip resurfacing femoral component ESKA Typ BS with 4.5 kN or by hand does not seem to cause fractures of the femoral head. Georg Thieme Verlag KG Stuttgart, New York.

Ion Beam Etching: Replication of Micro Nano-structured 3D Stencil Masks

International Nuclear Information System (INIS)

Weber, Patrick; Guibert, Edouard; Mikhailov, Serguei; Bruegger, Juergen; Villanueva, Guillermo

2009-01-01

Ion beam LIGA allows the etching of 3D nano-structures by direct writing with a nano-sized beam. However, this is a relatively time consuming process. We propose here another approach for etching structures on large surfaces and faster, compared to the direct writing process. This approach consists of replicating 3D structured masks, by scanning an unfocused ion beam. A polymer substrate is placed behind the mask, as in UV photolithography. But the main advantage is that the 3D structure of the mask can be replicated into the polymer. For that purpose, the masks (developped at LMIS1, EPFL) are made of a silicon nitride membrane 100 nm thick, on which 3D gold structures up to 200 nm thick, are deposited. The 3D Au structures are made with the nanostencil method, based on successive gold deposition. The IMA institute, from HE-Arc, owns a High Voltage Engineering 1.7 MV Tandetron with both solid and gaseous negative ion sources, able to generate ions from almost every chemical element in a broad range of energies comprised between 400 keV and 6.8 MeV. The beam composition and energy are chosen in such a way, that ions lose a significant fraction of their energy when passing through the thickest regions of the mask. Ions passing through thinner regions of the mask loose a smaller fraction of their energy and etch the polymer with larger thicknesses, allowing a replication of the mask into the polymer. For our trials, we have used a carbon beam with an energy of 500 keV. The beam was focussed to a diameter of 5 mm with solid slits, in order to avoid border effects and thus ensure a homogeneous dose distribution on the beam diameter. The feasibility of this technique has been demonstrated, allowing industrial applications for micro-mould fabrication, micro-fluidics and micro-optics.

Histogram-driven cupping correction (HDCC) in CT

Science.gov (United States)

Kyriakou, Y.; Meyer, M.; Lapp, R.; Kalender, W. A.

2010-04-01

Typical cupping correction methods are pre-processing methods which require either pre-calibration measurements or simulations of standard objects to approximate and correct for beam hardening and scatter. Some of them require the knowledge of spectra, detector characteristics, etc. The aim of this work was to develop a practical histogram-driven cupping correction (HDCC) method to post-process the reconstructed images. We use a polynomial representation of the raw-data generated by forward projection of the reconstructed images; forward and backprojection are performed on graphics processing units (GPU). The coefficients of the polynomial are optimized using a simplex minimization of the joint entropy of the CT image and its gradient. The algorithm was evaluated using simulations and measurements of homogeneous and inhomogeneous phantoms. For the measurements a C-arm flat-detector CT (FD-CT) system with a 30×40 cm2 detector, a kilovoltage on board imager (radiation therapy simulator) and a micro-CT system were used. The algorithm reduced cupping artifacts both in simulations and measurements using a fourth-order polynomial and was in good agreement to the reference. The minimization algorithm required less than 70 iterations to adjust the coefficients only performing a linear combination of basis images, thus executing without time consuming operations. HDCC reduced cupping artifacts without the necessity of pre-calibration or other scan information enabling a retrospective improvement of CT image homogeneity. However, the method can work with other cupping correction algorithms or in a calibration manner, as well.

A micro-CT research on early faience:a case study of Peng state faience

International Nuclear Information System (INIS)

Gu Zhou; Yang Yimin; Wang Ning; Wang Changsui; Xie Yaoting; Xiao Tiqiao

2012-01-01

Faience is supposed to be the precursor of ancient glass. Studies on Chinese faience are of help in understanding the origin and development of Chinese ancient glass. In this paper, non-destructive methods of SR-μCT, XRD and EDXRF are used to analyze a faience bead from Peng state in Western Zhou period (BC1046-BC771). The results show that the bead body is composed of micro quartz particles, and the body is denser than that of Western faience. The manufacture procedure can be deduced as follows: based on a cylinder core, the quartz particles were piled to form the body, which was then glazed and heated; after that the core was stripped. This technology was influenced by the bronze and protoporcelain production. Micro CT has great potential to study microstructure of ancient faience. (authors)

A method of measuring micro-impulse with torsion pendulum based on multi-beam laser heterodyne

Science.gov (United States)

Li, Yan-Chao; Wang, Chun-Hui

2012-02-01

In this paper, we propose a novel method of multi-beam laser heterodyne measurement for micro-impulse. The measurement of the micro-impulse, which is converted into the measurement of the small tuning angle of the torsion pendulum, is realized by considering the interaction between pulse laser and working medium. Based on Doppler effect and heterodyne technology, the information regarding the small tuning angle is loaded to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, thereby obtaining many values of the small tuning angle after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, the small tuning angle can be obtained accurately and the value of the micro-impulse can eventually be calculated. Using Polyvinylchlorid+2%C as a working medium, this novel method is used to simulate the value of the micro-impulse by MATLAB which is generated by considering the interaction between the pulse laser and the working medium, the obtained result shows that the relative error of this method is just 0.5%.

A method of measuring micro-impulse with torsion pendulum based on multi-beam laser heterodyne

International Nuclear Information System (INIS)

Li Yan-Chao; Wang Chun-Hui

2012-01-01

In this paper, we propose a novel method of multi-beam laser heterodyne measurement for micro-impulse. The measurement of the micro-impulse, which is converted into the measurement of the small tuning angle of the torsion pendulum, is realized by considering the interaction between pulse laser and working medium. Based on Doppler effect and heterodyne technology, the information regarding the small tuning angle is loaded to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, thereby obtaining many values of the small tuning angle after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, the small tuning angle can be obtained accurately and the value of the micro-impulse can eventually be calculated. Using Polyvinylchlorid+2%C as a working medium, this novel method is used to simulate the value of the micro-impulse by MATLAB which is generated by considering the interaction between the pulse laser and the working medium, the obtained result shows that the relative error of this method is just 0.5%. (general)

Size-dependent nonlinear bending of micro/nano-beams made of nanoporous biomaterials including a refined truncated cube cell

Science.gov (United States)

Sahmani, S.; Aghdam, M. M.

2017-12-01

Morphology and pore size plays an essential role in the mechanical properties as well as the associated biological capability of a porous structure made of biomaterials. The objective of the current study is to predict the Young's modulus and Poisson's ratio of nanoporous biomaterials including refined truncated cube cells based on a hyperbolic shear deformable beam model. Analytical relationships for the mechanical properties of nanoporous biomaterials are given as a function of the refined cell's dimensions. After that, the size dependency in the nonlinear bending behavior of micro/nano-beams made of such nanoporous biomaterials is analyzed using the nonlocal strain gradient elasticity theory. It is assumed that the micro/nano-beam has one movable end under axial compression in conjunction with a uniform distributed lateral load. The Galerkin method together with an improved perturbation technique is employed to propose explicit analytical expression for nonlocal strain gradient load-deflection curves of the micro/nano-beams made of nanoporous biomaterials subjected to uniform transverse distributed load. It is found that through increment of the pore size, the micro/nano-beam will undergo much more deflection corresponding to a specific distributed load due to the reduction in the stiffness of nanoporous biomaterial. This pattern is more prominent for lower value of applied axial compressive load at the free end of micro/nano-beam.

Present and future in the use of micro-CT scanner 3D analysis for the study of dental and root canal morphology.

Science.gov (United States)

Grande, Nicola M; Plotino, Gianluca; Gambarini, Gianluca; Testarelli, Luca; D'Ambrosio, Ferdinando; Pecci, Raffaella; Bedini, Rossella

2012-01-01

The goal of the present article is to illustrate and analyze the applications and the potential of microcomputed tomography (micro-CT) in the analysis of tooth anatomy and root canal morphology. The authors performed a micro-CT analysis of the following different teeth: maxillary first molars with a second canal in the mesiobuccal (MB) root, mandibular first molars with complex anatomy in the mesial root, premolars with single and double roots and with complicated apical anatomy. The hardware device used in this study was a desktop X-ray microfocus CT scanner (SkyScan 1072, SkyScan bvba, Aartselaar, Belgium). A specific software ResolveRT Amira (Visage Imaging) was used for the 3D analysis and imaging. The authors obtained three-dimensional images from 15 teeth. It was possible to precisely visualize and analyze external and internal anatomy of teeth, showing the finest details. Among the 5 upper molars analyzed, in three cases, the MB canals joined into one canal, while in the other two molars the two mesial canals were separate. Among the lower molars two of the five samples exhibited a single canal in the mesial root, which had a broad, flat appearance in a mesiodistal dimension. In the five premolar teeth, the canals were independent; however, the apical delta and ramifications of the root canals were quite complex. Micro-CT offers a simple and reproducible technique for 3D noninvasive assessment of the anatomy of root canal systems.

Present and future in the use of micro-CT scanner 3D analysis for the study of dental and root canal morphology

Directory of Open Access Journals (Sweden)

Nicola M. Grande

2012-01-01

Full Text Available The goal of the present article is to illustrate and analyze the applications and the potential of microcomputed tomography (micro-CT in the analysis of tooth anatomy and root canal morphology. The authors performed a micro-CT analysis of the following different teeth: maxillary first molars with a second canal in the mesiobuccal (MB root, mandibular first molars with complex anatomy in the mesial root, premolars with single and double roots and with complicated apical anatomy. The hardware device used in this study was a desktop X-ray microfocus CT scanner (SkyScan 1072, SkyScan bvba, Aartselaar, Belgium. A specific software ResolveRT Amira (Visage Imaging was used for the 3D analysis and imaging. The authors obtained three-dimensional images from 15 teeth. It was possible to precisely visualize and analyze external and internal anatomy of teeth, showing the finest details. Among the 5 upper molars analyzed, in three cases, the MB canals joined into one canal, while in the other two molars the two mesial canals were separate. Among the lower molars two of the five samples exhibited a single canal in the mesial root, which had a broad, flat appearance in a mesiodistal dimension. In the five premolar teeth, the canals were independent; however, the apical delta and ramifications of the root canals were quite complex. Micro-CT offers a simple and reproducible technique for 3D noninvasive assessment of the anatomy of root canal systems.

Diagnostic accuracy of cone-beam CT in the assessment of mandibular invasion of lower gingival carcinoma: Comparison with conventional panoramic radiography

International Nuclear Information System (INIS)

Momin, Mohammad A.; Okochi, Kiyoshi; Watanabe, Hiroshi; Imaizumi, Akiko; Omura, Ken; Amagasa, Teruo; Okada, Norihiko; Ohbayashi, Naoto; Kurabayashi, Tohru

2009-01-01

Purpose: To evaluate the diagnostic accuracy of cone-beam CT in assessing mandibular invasion by lower gingival carcinoma and compare it with that of panoramic radiography. Patients and methods: Fifty patients with squamous cell carcinoma of the lower gingiva who were examined by both panoramic radiography and cone-beam CT before surgery were included in this study. Five radiologists used a 6-point rating scale to independently evaluate cone-beam CT and panoramic images for the presence or absence of alveolar bone and mandibular canal involvement by tumor. Using the histopathogical findings as the gold standard, we calculated and compared the area under the receiver operating characteristic curve (Az value) and the sensitivity and specificity of the two imaging modalities. Results: In evaluations of both alveolar bone and mandibular canal involvement, the mean Az value for cone-beam CT (0.918 and 0.977, respectively) was significantly higher than that for panoramic radiography (0.793 and 0.872, respectively). The mean sensitivity for cone-beam CT (89% and 99%, respectively) was significantly higher than that for panoramic radiography (73% and 56%, respectively). There was no significant difference in the mean specificity. While cone-beam CT could provide high-resolution three-dimensional images, the image quality around the alveolar crest was often hampered by severe dental artifacts and image noise, resulting in difficulties in detecting subtle alveolar invasion. Conclusion: Cone-beam CT was significantly superior to panoramic radiography in evaluating mandibular invasion by lower gingival carcinoma. Its diagnostic value in detecting subtle alveolar invasion, however, may be limited by severe dental artifacts and image noise.

Three-dimensional analysis of mesiobuccal root canal of Japanese maxillary first molar using Micro-CT

International Nuclear Information System (INIS)

Yamada, Masashi; Ide, Yoshinobu; Matsunaga, Satoru; Kato, Hiroshi; Nakagawa, Kan-Ichi

2011-01-01

The objective of this study was to three-dimensionally observe the morphological characteristics of mesiobuccal root canals of Japanese maxillary first molars using microcomputed tomography (Micro-CT) and classify root canal variations. This study used 90 maxillary first molars. Three-dimensional reconstruction was performed using data obtained by Micro-CT, and cross-sections of the root canals were observed. Moreover, the root canal morphology was classified by the configuration and root canal diameter, and was evaluated for occurrence using the classification by Weine et al. (1969) as a reference. Overall, single root canals were observed in 44.4%, incomplete separation root canals in 22.3%, and completely separate root canals (upper and lower separation root canals) in 33.3%. Mesiobuccal root canals often had intricate configurations, and accessory root canals (lateral canals and apical ramifications) were observed in most of the mesiobuccal root canals (76.7%), irrespective of whether there were ramifications of the main root canals. While there were no marked differences in the incidence of root canal ramifications between this study and earlier reports, the incidence of accessory root canals was higher in this study. This result may be explained by the far more superior visualization ability of Micro-CT than conventional methods, which allowed the detection of microscopic apical ramifications previously difficult to observe. (author)

Low-dose megavoltage cone-beam CT for radiation therapy

International Nuclear Information System (INIS)

Pouliot, Jean; Bani-Hashemi, Ali; Chen, Josephine; Svatos, Michelle; Ghelmansarai, Farhad; Mitschke, Matthias; Aubin, Michele; Xia Ping; Morin, Olivier; Bucci, Kara; Roach, Mack; Hernandez, Paco; Zheng Zirao; Hristov, Dimitre; Verhey, Lynn

2005-01-01

Purpose: The objective of this work was to demonstrate the feasibility of acquiring low-exposure megavoltage cone-beam CT (MV CBCT) three-dimensional (3D) image data of sufficient quality to register the CBCT images to kilovoltage planning CT images for patient alignment and dose verification purposes. Methods and materials: A standard clinical 6-MV Primus linear accelerator, operating in arc therapy mode, and an amorphous-silicon (a-Si) flat-panel electronic portal-imaging device (EPID) were employed. The dose-pulse rate of a 6-MV Primus accelerator beam was windowed to expose an a-Si flat panel by using only 0.02 to 0.08 monitor units (MUs) per image. A triggered image-acquisition mode was designed to produce a high signal-to-noise ratio without pulsing artifacts. Several data sets were acquired for an anthropomorphic head phantom and frozen sheep and pig cadaver heads, as well as for a head-and-neck cancer patient on intensity-modulated radiotherapy (IMRT). For each CBCT image, a set of 90 to 180 projection images incremented by 1 deg to 2 deg was acquired. The two-dimensional (2D) projection images were then synthesized into a 3D image by use of cone-beam CT reconstruction. The resulting MV CBCT image set was used to visualize the 3D bony anatomy and some soft-tissue details. The 3D image registration with the kV planning CT was performed either automatically by application of a maximization of mutual information (MMI) algorithm or manually by aligning multiple 2D slices. Results: Low-noise 3D MV CBCT images without pulsing artifacts were acquired with a total delivered dose that ranged from 5 to 15 cGy. Acquisition times, including image readout, were on the order of 90 seconds for 180 projection images taken through a continuous gantry rotation of 180 deg . The processing time of the data required an additional 90 seconds for the reconstruction of a 256 3 cube with 1.0-mm voxel size. Implanted gold markers (1 mm x 3 mm) were easily visible for all exposure

SimDoseCT: dose reporting software based on Monte Carlo simulation for a 320 detector-row cone-beam CT scanner and ICRP computational adult phantoms

Science.gov (United States)

Cros, Maria; Joemai, Raoul M. S.; Geleijns, Jacob; Molina, Diego; Salvadó, Marçal

2017-08-01

This study aims to develop and test software for assessing and reporting doses for standard patients undergoing computed tomography (CT) examinations in a 320 detector-row cone-beam scanner. The software, called SimDoseCT, is based on the Monte Carlo (MC) simulation code, which was developed to calculate organ doses and effective doses in ICRP anthropomorphic adult reference computational phantoms for acquisitions with the Aquilion ONE CT scanner (Toshiba). MC simulation was validated by comparing CTDI measurements within standard CT dose phantoms with results from simulation under the same conditions. SimDoseCT consists of a graphical user interface connected to a MySQL database, which contains the look-up-tables that were generated with MC simulations for volumetric acquisitions at different scan positions along the phantom using any tube voltage, bow tie filter, focal spot and nine different beam widths. Two different methods were developed to estimate organ doses and effective doses from acquisitions using other available beam widths in the scanner. A correction factor was used to estimate doses in helical acquisitions. Hence, the user can select any available protocol in the Aquilion ONE scanner for a standard adult male or female and obtain the dose results through the software interface. Agreement within 9% between CTDI measurements and simulations allowed the validation of the MC program. Additionally, the algorithm for dose reporting in SimDoseCT was validated by comparing dose results from this tool with those obtained from MC simulations for three volumetric acquisitions (head, thorax and abdomen). The comparison was repeated using eight different collimations and also for another collimation in a helical abdomen examination. The results showed differences of 0.1 mSv or less for absolute dose in most organs and also in the effective dose calculation. The software provides a suitable tool for dose assessment in standard adult patients undergoing CT

CT-Based Micro-Mechanical Approach to Predict Response of Closed-Cell Porous Biomaterials to Low-Velocity Impact

Directory of Open Access Journals (Sweden)

Mehrdad Koloushani

2018-03-01

Full Text Available In this study, a new numerical approach based on CT-scan images and finite element (FE method has been used to predict the mechanical behavior of closed-cell foams under impact loading. Micro-structural FE models based on CT-scan images of foam specimens (elastic-plastic material model with material constants of bulk aluminum and macro-mechanical FE models (with crushable foam material model with material constants of foams were constructed. Several experimental tests were also conducted to see which of the two noted (micro- or macro- mechanical FE models can better predict the deformation and force-displacement curves of foams. Compared to the macro-structural models, the results of the micro-structural models were much closer to the corresponding experimental results. This can be explained by the fact that the micro-structural models are able to take into account the interaction of stress waves with cell walls and the complex pathways the stress waves have to go through, while the macro-structural models do not have such capabilities. Despite their high demand for computational resources, using micro-scale FE models is very beneficial when one needs to understand the failure mechanisms acting in the micro-structure of a foam in order to modify or diminish them.

Micro-CT evaluation and histological analysis of screw-bone interface of expansive pedicle screw in osteoporotic sheep.

Science.gov (United States)

Wan, Shi-yong; Lei, Wei; Wu, Zi-xiang; Lv, Rong; Wang, Jun; Fu, Suo-chao; Li, Bo; Zhan, Ce

2008-04-01

To investigate the properties of screw-bone interface of expansive pedicle screw (EPS) in osteoporotic sheep by micro-CT and histological observation. Six female sheep with bilateral ovariectomy-induced osteoporosis were employed in this experiment. After EPS insertion in each femoral condyle, the sheep were randomly divided into two groups: 3 sheep were bred for 3 months (Group A), while the other 3 were bred for 6 months (Group B). After the animals being killed, the femoral condyles with EPS were obtained, which were three-dimensionally-imaged and reconstructed by micro-CT. Histological evaluation was made thereafter. The trabecular microstructure was denser at the screw-bone interface than in the distant parts in expansive section, especially within the spiral marking. In the non-expansive section, however, there was no significant difference between the interface and the distant parts. The regions of interest (ROI) adjacent to EPS were reconstructed and analyzed by micro-CT with the same thresholds. The three-dimensional (3-D) parameters, including tissue mineral density (TMD), bone volume fraction (BVF, BV/TV), bone surface/bone volume (BS/BV) ratio, trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp), were significantly better in expansive sections than non-expansive sections (P less than 0.05). Histologically, newly-formed bony trabeculae crawled along the expansive fissures and into the center of EPS. The newly-formed bones, as well as the bones at the bone-screw interface, closely contacted with the EPS and constructed four compartments. The findings of the current study, based on micro-CT and histological evaluation, suggest that EPS can significantly provide stabilization in osteoporotic cancellous bones.

Molar cusp deformation evaluated by micro-CT and enamel crack formation to compare incremental and bulk-filling techniques.

Science.gov (United States)

Oliveira, Laís Rani Sales; Braga, Stella Sueli Lourenço; Bicalho, Aline Arêdes; Ribeiro, Maria Tereza Hordones; Price, Richard Bengt; Soares, Carlos José

2018-07-01

To describe a method of measuring the molar cusp deformation using micro-computed tomography (micro-CT), the propagation of enamel cracks using transillumination, and the effects of hygroscopic expansion after incremental and bulk-filling resin composite restorations. Twenty human molars received standardized Class II mesio-occlusal-distal cavity preparations. They were restored with either a bulk-fill resin composite, X-tra fil (XTRA), or a conventional resin composite, Filtek Z100 (Z100). The resin composites were tested for post-gel shrinkage using a strain gauge method. Cusp deformation (CD) was evaluated using the images obtained using a micro-CT protocol and using a strain-gauge method. Enamel cracks were detected using transillumination. The post-gel shrinkage of Z100 was higher than XTRA (P cracks than XTRA (P = 0.012). Micro-CT was an effective method for evaluating the cusp deformation. Transillumination was effective for detecting enamel cracks. There were fewer negative effects of polymerization shrinkage in bulk-fill resin restorations using XTRA than for the conventional incremental filling technique using conventional composite resin Z100. Shrinkage and cusp deformation are directly related to the formation of enamel cracks. Cusp deformation and crack propagation may increase the risk of tooth fracture. Copyright © 2018 Elsevier Ltd. All rights reserved.

Micro/nano analysis of tooth microstructures by Focused Ion Beam (FIB cross-sectioning

Directory of Open Access Journals (Sweden)

Meltem Sezen

2017-04-01

Full Text Available Since dental structures are hard and fragile, cross-sectioning of these materials using ultramicrotomy and other techniques and following micro and nano analysis cause problems. The use of FIB-SEM dual beam platforms is the most convenient solution for investigating the microstructures, site-specifically and in certain geometries. Dual beam platforms allow for imaging at high magnifications and resolutions and simultaneous elemental analysis. In this study, the micro/nano-structural and chemical differences were revealed in dentin and enamel samples. The investigation of dental tissues having different morphologies and chemical components by ion-cross-sectioning is important for the use of FIB-SEM platforms in dentistry in Turkey.

An experimental study on the influence of scatter and beam hardening in x-ray CT for dimensional metrology

International Nuclear Information System (INIS)

Lifton, J J; McBride, J W; Malcolm, A A

2016-01-01

Scattered radiation and beam hardening introduce artefacts that degrade the quality of data in x-ray computed tomography (CT). It is unclear how these artefacts influence dimensional measurements evaluated from CT data. Understanding and quantifying the influence of these artefacts on dimensional measurements is required to evaluate the uncertainty of CT-based dimensional measurements. In this work the influence of scatter and beam hardening on dimensional measurements is investigated using the beam stop array scatter correction method and spectrum pre-filtration for the measurement of an object with internal and external cylindrical dimensional features. Scatter and beam hardening are found to influence dimensional measurements when evaluated using the ISO50 surface determination method. On the other hand, a gradient-based surface determination method is found to be robust to the influence of artefacts and leads to more accurate dimensional measurements than those evaluated using the ISO50 method. In addition to these observations the GUM method for evaluating standard measurement uncertainties is applied and the standard measurement uncertainty due to scatter and beam hardening is estimated. (paper)

Synchrotron μCT Imaging of Bone, Titanium implants and Bone Substitutes -a Systematic Review of the Literature

DEFF Research Database (Denmark)

Neldam, Camilla Albeck; Pinholt, Else Marie

2014-01-01

Today x-ray micro computer tomography (μCT) imaging is used to investigate bone microarchitecture. μCT imaging is obtained by polychromatic x-ray beams, resulting in images with beam hardening artifacts, resolution levels at 10 μm, geometrical blurring, and lack of contrasts. When μCT is coupled...... to synchrotron sources (SRμCT) a spatial resolution up to one tenth of a μm may be achieved. A review of the literature concerning SRμCT was performed to investigate its usability and its strength in visualizing fine bone structures, vessels, and microarchitecture of bone. Although mainly limited to in vitro...... examinations, SRμCT is considered as a gold standard to image trabecular bone microarchitecture since it is possible in a 3D manner to visualize fine structural elements within mineralized tissue such as osteon boundaries, rods and plates structures, cement lines, and differences in mineralization...

High Accuracy Beam Current Monitor System for CEBAF'S Experimental Hall A

International Nuclear Information System (INIS)

J. Denard; A. Saha; G. Lavessiere

2001-01-01

CEBAF accelerator delivers continuous wave (CW) electron beams to three experimental Halls. In Hall A, all experiments require continuous, non-invasive current measurements and a few experiments require an absolute accuracy of 0.2 % in the current range from 1 to 180 (micro)A. A Parametric Current Transformer (PCT), manufactured by Bergoz, has an accurate and stable sensitivity of 4 (micro)A/V but its offset drifts at the muA level over time preclude its direct use for continuous measurements. Two cavity monitors are calibrated against the PCT with at least 50 (micro)A of beam current. The calibration procedure suppresses the error due to PCT's offset drifts by turning the beam on and off, which is invasive to the experiment. One of the goals of the system is to minimize the calibration time without compromising the measurement's accuracy. The linearity of the cavity monitors is a critical parameter for transferring the accurate calibration done at high currents over the whole dynamic range. The method for measuring accurately the linearity is described

Complete synchronization condition in a network of piezoelectric micro-beam

International Nuclear Information System (INIS)

Taffoti Yolong, V.Y.; Woafo, P.

2007-10-01

This work deals with the dynamics of a network of piezoelectric micro-beams. The complete synchronization condition for this class of chaotic nonlinear electromechanical systems devices with nearest-neighbor diffusive coupling is studied. The nonlinearities on the device studied here are both on the electrical component and on the mechanical one. The investigation is made for the case of a large number of discrete piezoelectric disks coupled. The problem of chaos synchronization is described and converted into the analysis of stability of the system via its differential equations. We show that the complete synchronization of N identical coupled nonlinear chaotic systems having the shift invariant coupling schemes can be calculated from the synchronization of two of them coupled in both directions. According to analytical, semi-analytical predictions and numerical calculations, the transition boundaries for chaos synchronization state in the coupled system are determined as a function of the increasing number of oscillators. (author)

A beam test of prototype time projection chamber using micro ...

Indian Academy of Sciences (India)

High Energy Accelerator Organization (KEK), Tsukuba 305-0801, Japan. E-mail: makoto.kobayashi.exp@kek.jp. Abstract. We conducted a series of beam tests of prototype TPCs for the international linear collider (ILC) experiment, equipped with an MWPC, a MicroMEGAS, or GEMs as a readout device. The prototype ...

Construction, test and operation in a high intensity beam of a small system of micro-strip gas chambers

Science.gov (United States)

Barr, A.; Bachmann, S.; Boimska, B.; Bouclier, R.; Braem, A.; Camps, C.; Capeáns, M.; Commichau, V.; Dominik, W.; Flügge, G.; Gómez, F.; Hammarstrom, R.; Hangarter, K.; Hoch, M.; Labbé, J. C.; Macke, D.; Manzin, G.; Meijers, F.; Million, G.; Muhlemann, K.; Nagaslaev, V.; Peisert, A.; Ropelewski, L.; Runolfsson, O.; Sauli, F.; Schulte, R.; Schulz, M.; Sharma, A.; Shekhtman, L.; Wolff, C.

1998-02-01

We describe the construction, test and installation procedures, and the experience gained with the operation of a small but complete system of high-rate Micro-Strip Gas Chambers, made on thin borosilicate glass with a diamond-like coating with chromium or gold strips. A set of detectors, fully equipped with read-out electronics and each with an active area of 100 × 100 mm 2, was exposed during six months to a high-intensity muon beam at CERN with a peak intensity of ˜ 10 4 mm -2s -1. Continuous monitoring of the performance of the chambers during the beam runs allowed the evaluation of detection efficiency and the monitoring of accidental rates, as well as the study of ambient induced variations and aging in realistic beam conditions. No significant difference has been found in the operation of under-and over-coated plates. Efficiencies could reach ˜ 98% in best operating conditions, although local lower values were often observed due to missing channels (open strips, broken bonds and dead electronic channels). The long-term operation of the chambers has been more difficult than expected, with the appearance of break-downs and loss of efficiency in some detectors, possibly induced by the presence of small gas leaks, to water permeation or to residual reactivity of the quencher gas (dimethylether).

Micro-computerised tomography optimisation for the measurement of bone mineral density around titanium dental implants

International Nuclear Information System (INIS)

Park, C.; Swain, M.; Duncan, W.

2010-01-01

Titanium dental implants (screws) are commonly used to replace missing teeth by forming a biological union with bone ('osseointegration'). Micro-computerised tomography (μCT) may be useful for measuring bone mineral density around dental implants. Major issues arise because of various artefacts that occur with polychromatic X-rays associated bench type instruments that may compromise interpretation of the observations. In this study various approaches to minimise artefacts such as; beam hardening, filtering and edge effects are explored with a homogeneous polymeric material, Teflon, with and without an implant present. The implications of the limitations of using such polychromatic μCT systems to quantify bone mineral density adjacent to the implant are discussed. (author)

Cone Beam Micro-CT System for Small Animal Imaging and Performance Evaluation

Directory of Open Access Journals (Sweden)

Shouping Zhu

2009-01-01

in this paper. Experimental results show that the system is suitable for small animal imaging and is adequate to provide high-resolution anatomic information for bioluminescence tomography to build a dual modality system.

Evaluation of positioning errors of the patient using cone beam CT megavoltage; Evaluacion de errores de posicionamiento del paciente mediante Cone Beam CT de megavoltaje

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Garcia Ruiz-Zorrilla, J.; Fernandez Leton, J. P.; Zucca Aparicio, D.; Perez Moreno, J. M.; Minambres Moro, A.

2013-07-01

Image-guided radiation therapy allows you to assess and fix the positioning of the patient in the treatment unit, thus reducing the uncertainties due to the positioning of the patient. This work assesses errors systematic and errors of randomness from the corrections made to a series of patients of different diseases through a protocol off line of cone beam CT (CBCT) megavoltage. (Author)

Intense, brilliant micro γ-beams in nuclear physics and applications

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Habs, D.; Gasilov, S.; Lang, C.; Thirolf, P. G.; Jentschel, M.; Diehl, R.; Schroer, C.; Barty, C. P. J.; Zamfir, N. V.

2011-06-01

The upcoming γ facilities MEGa-Ray (Livermore) and ELI-NP (Bucharest) will have a 105 times higher γ flux F0 = 1013/s and a ~30 times smaller band width (ΔEγ/Eγ = BW ~ 10-3) than the presently best γ beam facility. They will allow to extract a small γ beam of about 30 - 100 μm radius 1 m behind the γ production point, containing the dominant γ energy band width. One can collimate the γ beam down to ΘBW = √ BW/ γe , where γe = Ee/ mec2 is a measure of the energy Ee of the electron beam, from which the γ beam is produced by Compton back-scattering. Due to the γ energy - angle correlation, the angular collimation results at the same time in a reduction of the γ beam band width without loss of "good" γ quanta, however, the primary γ flux F0is reduced to about Fcoll ~ F0 . 1.5 . ΔEγ/Eγ. For γ rays in the (0.1-100) MeV range, the negative real part δ of the index of refraction n = 1- δ + iβ from coherent Rayleigh scattering (virtual photo effect) dominates over the positive δ contributions from coherent virtual Compton scattering and coherent virtual pair creation scattering (Delbrück scattering). The very small absolute value |δ| ~ 10-6 - 10-9 of the index of refraction of matter for hard X-rays and γ-rays and its negative sign--in contrast to usual optics--results in a very different γ-ray optics, e.g. focusing lenses become concave and we use stacks of N optimized lenses. It requires very small radii of curvature of the γ lenses and thus very small γ beam radii. This leads to a technical new solution, where the primary γ beam is subdivided into M γ beamlets, which do not interfere with each other, but contribute with their independent intensities. We send the γ beamlets into a two-dimensional array of closely packed cylindrical parabolic refractive lenses, where N ~ 103 lenses with very small radius of curvature are stacked behind each other, leading to contracted beam spots in one dimension. With a second 1D lens system turned by

An experimental system for coiled tubing partial underbalanced drilling (CT-PUBD) technique

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Shi, H. Z.; Ji, Z. S.; Zhao, H. Q.; Chen, Z. L.; Zhang, H. Z.

2018-05-01

To improve the rate of penetration (ROP) in hard formations, a new high-speed drilling technique called Coiled Tubing Partial Underbalanced Drilling (CT-PUBD) is proposed. This method uses a rotary packer to realize an underbalanced condition near the bit by creating a micro-annulus and an overbalanced condition at the main part of the annulus. A new full-scale laboratory experimental system is designed and set up to study the hydraulic characteristics and drilling performance of this method. The system is composed of a drilling system, circulation system, and monitor system, including three key devices, namely, cuttings discharge device, rotary packer, and backflow device. The experimental results showed that the pressure loss increased linearly with the flow rate of the drilling fluid. The high drilling speed of CT-PUBD proved it a better drilling method than the conventional drilling. The experimental system may provide a fundamental basis for the research of CT-PUBD, and the results proved that this new method is feasible in enhancing ROP and guaranteeing the drilling safety.

Truncation artifact suppression in cone-beam radionuclide transmission CT using maximum likelihood techniques: evaluation with human subjects

International Nuclear Information System (INIS)

Manglos, S.H.

1992-01-01

Transverse image truncation can be a serious problem for human imaging using cone-beam transmission CT (CB-CT) implemented on a conventional rotating gamma camera. This paper presents a reconstruction method to reduce or eliminate the artifacts resulting from the truncation. The method uses a previously published transmission maximum likelihood EM algorithm, adapted to the cone-beam geometry. The reconstruction method is evaluated qualitatively using three human subjects of various dimensions and various degrees of truncation. (author)

Analyses of the internal structure of the oscillating vibro-packed fuels by the micro focus X-rays CT method

International Nuclear Information System (INIS)

Mizuta, Yasutoshi

2003-02-01

The purpose of this study is to support the development of vibro-packed fuel technology at Japan Nuclear Cycle Development Institute. 3-dimensional (3-D) data was built from the multi-cross sectional images obtained by the micro focus X-rays CT method in the vibro-packed fuel models. The structural analyses were carried out about the obtained 3-D CT images. The packing-rate distribution and the density distribution were measured as well as the number distribution of particles, etc. Consequently, it is obtained that vibrate conditions and a vibrating state have strong correlation, and it is also shown that the 3-D analyses of the internal structure by the micro focus X-rays CT method are effective in performance evaluation of vibro-packed fuels. (author)

Investigation of practical approaches to evaluating cumulative dose for cone beam computed tomography (CBCT) from standard CT dosimetry measurements: a Monte Carlo study.

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Abuhaimed, Abdullah; Martin, Colin J; Sankaralingam, Marimuthu; Gentle, David J

2015-07-21

A function called Gx(L) was introduced by the International Commission on Radiation Units and Measurements (ICRU) Report-87 to facilitate measurement of cumulative dose for CT scans within long phantoms as recommended by the American Association of Physicists in Medicine (AAPM) TG-111. The Gx(L) function is equal to the ratio of the cumulative dose at the middle of a CT scan to the volume weighted CTDI (CTDIvol), and was investigated for conventional multi-slice CT scanners operating with a moving table. As the stationary table mode, which is the basis for cone beam CT (CBCT) scans, differs from that used for conventional CT scans, the aim of this study was to investigate the extension of the Gx(L) function to CBCT scans. An On-Board Imager (OBI) system integrated with a TrueBeam linac was simulated with Monte Carlo EGSnrc/BEAMnrc, and the absorbed dose was calculated within PMMA, polyethylene (PE), and water head and body phantoms using EGSnrc/DOSXYZnrc, where the body PE body phantom emulated the ICRU/AAPM phantom. Beams of width 40-500 mm and beam qualities at tube potentials of 80-140 kV were studied. Application of a modified function of beam width (W) termed Gx(W), for which the cumulative dose for CBCT scans f (0) is normalized to the weighted CTDI (CTDIw) for a reference beam of width 40 mm, was investigated as a possible option. However, differences were found in Gx(W) with tube potential, especially for body phantoms, and these were considered to be due to differences in geometry between wide beams used for CBCT scans and those for conventional CT. Therefore, a modified function Gx(W)100 has been proposed, taking the form of values of f (0) at each position in a long phantom, normalized with respect to dose indices f 100(150)x measured with a 100 mm pencil ionization chamber within standard 150 mm PMMA phantoms, using the same scanning parameters, beam widths and positions within the phantom. f 100(150)x averages the dose resulting from

Direct micro-CT observation confirms the induction of embolism upon xylem cutting under tension

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We used two different Synchrotron-based micro-CT facilities (SLS: Swiss Light Source, Villigen, Switzerland, and ALS: Advanced Light Source, Berkeley, CA USA) to test the excision artifact described by Wheeler et al. (2013). Specifically, we examined the impact of cutting xylem under tension and und...

Influence of metal artifacts on in vivo micro-CT for orthodontic mini-implants

International Nuclear Information System (INIS)

Ejima, Ken-ichiro; Omasa, Saori; Motoyoshi, Mitsuru; Arai, Yoshinori; Kai, Yukiko; Amemiya, Toshihiko; Yamada, Hisaya; Honda, Kazuya; Shimizu, Noriyoshi

2012-01-01

This study aimed to show the effects of metal artifacts on the in vivo micro-CT of mini-implants by measuring bone volume. We drilled a hole in the cortical bone of a rat tibia and embedded a titanium orthodontic mini-implant (diameter, 1.5 mm) in the hole. Twelve individually weighed hydroxyapatite grains (HA grains) were placed around the implant either by one dentist (method 1) or separately by 12 dentists (method 2). In vivo micro-CT was used to scan the model after placement of each grain to measure increases and decreases in bone volume voxel number. The subtracted bone voxel volume increased with HA weight in both methods. Simple linear regression analysis showed a significant correlation between weight and volume in both methods (method 1: regression coefficient: 516.502, P<0.05; method 2: regression coefficient: 4837.432, P<0.05). Metal artifacts did not appear to influence measurements of bone volume, although further studies are required to determine the effect of thicker implants. (author)

Advances in lasers and optical micro-nano-systems

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Laurell, F.; Fazio, E.

2010-09-01

Lasers represent a well consolidated technology: nevertheless, research in this field remains very active and productive, in both basic and applied directions. At the moment significant attention is given to those sources that bring together high power and compactness. Such high power lasers find important applications for material treatments and such applications are presented by Ehsani et al and Saiedeh Saghafi et al, in the treatment of dielectric thin films (Alteration of optical and morphological properties of polycarbonate illuminated by visible/IR laser beams) or of biological tissues like pistachio seeds (Investigating the effects of laser beams (532 and 660 nm) in annihilation of pistachio mould fungus using spectrophotometry analysis). In particular the latter paper show how laser sources can find very important applications in new domains, preserving goods and food without the need for preservatives or pesticides by simply sterilizing them using light. Optical Micro and Nano Systems presents a new domain for exploration. In this framework this special issue is very attractive, because it assembles papers reporting new results in three directions: new techniques for monitoring integrated micro- and nano-systems, new integrated systems and novel high performance metamaterial configurations. Integrated micro-components can be monitored and controlled using reflectance measurements as presented by Piombini et al (Toward the reflectance measurement of micro components). Speckle formation during laser beam reflection can also be a very sophisticated tool for detecting ultra-precise displacements, as presented by Filter et al (High resolution displacement detection with speckles : accuracy limits in linear displacement speckle metrology). Three dimensional integrated optical structures is indeed a big challenge and a peculiarity of photonics, they can be formed through traditional holography or using more sophisticated and novel ! technologies. Thus, special

Tooth labeling in cone-beam CT using deep convolutional neural network for forensic identification

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Miki, Yuma; Muramatsu, Chisako; Hayashi, Tatsuro; Zhou, Xiangrong; Hara, Takeshi; Katsumata, Akitoshi; Fujita, Hiroshi

2017-03-01

In large disasters, dental record plays an important role in forensic identification. However, filing dental charts for corpses is not an easy task for general dentists. Moreover, it is laborious and time-consuming work in cases of large scale disasters. We have been investigating a tooth labeling method on dental cone-beam CT images for the purpose of automatic filing of dental charts. In our method, individual tooth in CT images are detected and classified into seven tooth types using deep convolutional neural network. We employed the fully convolutional network using AlexNet architecture for detecting each tooth and applied our previous method using regular AlexNet for classifying the detected teeth into 7 tooth types. From 52 CT volumes obtained by two imaging systems, five images each were randomly selected as test data, and the remaining 42 cases were used as training data. The result showed the tooth detection accuracy of 77.4% with the average false detection of 5.8 per image. The result indicates the potential utility of the proposed method for automatic recording of dental information.

Nondestructive Analysis of Apollo Samples by Micro-CT and Micro-XRF Analysis: A PET Style Examination

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Zeigler, Ryan A.

2014-01-01

An integral part of any sample return mission is the initial description and classification of returned samples by the preliminary examination team (PET). The goal of a PET is to characterize and classify the returned samples, making this information available to the general research community who can then conduct more in-depth studies on the samples. A PET strives to minimize the impact their work has on the sample suite, which often limits the PET work to largely visual measurements and observations like optical microscopy. More modern techniques can also be utilized by future PET to nondestructively characterize astromaterials in a more rigorous way. Here we present our recent analyses of Apollo samples 14321 and 14305 by micro-CT and micro-XRF (respectively), assess the potential for discovery of "new" Apollo samples for scientific study, and evaluate the usefulness of these techniques in future PET efforts.

Complex Odontoma: A Case Report with Micro-Computed Tomography Findings

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L. A. N. Santos

2016-01-01

Full Text Available Odontomas are the most common benign tumors of odontogenic origin. They are normally diagnosed on routine radiographs, due to the absence of symptoms. Histopathologic evaluation confirms the diagnosis especially in cases of complex odontoma, which may be confused during radiographic examination with an osteoma or other highly calcified bone lesions. The micro-CT is a new technology that enables three-dimensional analysis with better spatial resolution compared with cone beam computed tomography. Another great advantage of this technology is that the sample does not need special preparation or destruction in the sectioned area as in histopathologic evaluation. An odontoma with CBCT and microtomography images is presented in a 26-year-old man. It was first observed on panoramic radiographs and then by CBCT. The lesion and the impacted third molar were surgically excised using a modified Neumann approach. After removal, it was evaluated by histopathology and microtomography to confirm the diagnostic hypothesis. According to the results, micro-CT enabled the assessment of the sample similar to histopathology, without destruction of the sample. With further development, micro-CT could be a powerful diagnostic tool in future research.

The CMS Fast Beams Condition Monitor Backend Electronics based on MicroTCA technology

CERN Document Server

Zagozdzinska, Agnieszka Anna

2016-01-01

The Fast Beams Condition Monitor (BCM1F), upgraded for LHC Run II, is one sub-system of the Beam Radiation Instrumentation and Luminosity Project of the CMS experiment. It is based on 24 single crystal CVD diamond sensors. Each sensor is metallised with two pads, being read out by a dedicated fast frontend chip produced in 130 nm CMOS technology. Signals for real time monitoring are processed by custom-made back-end electronics to measure separately rates corresponding to LHC collision products, machine induced background and residual activation exploiting different arrival times. The system is built in MicroTCA technology and uses high speed analog-to-digital converters. The data processing module designed for the FPGA allows a distinguishing of collision and machine induced background, both synchronous to the LHC clock, from the residual activation products. In operational modes of high rates, consecutive events, spaced in time by less than 12.5 ns, may partially overlap. Hence, novel signal processing tec...

Shaping ability of single-file reciprocating and heat-treated multifile rotary systems: a micro-CT study.

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Marceliano-Alves, M F V; Sousa-Neto, M D; Fidel, S R; Steier, L; Robinson, J P; Pécora, J D; Versiani, M A

2015-12-01

To investigate changes in three-dimensional geometry, in various cross-sectional morphological parameters and in the centring ability of root canals prepared with different preparation systems using microcomputed tomographic imaging technology. Sixty-four mesial canals of mandibular molars were matched based on similar morphological dimensions using micro-CT evaluation and assigned to four experimental groups (n = 16), according to the canal preparation technique: Reciproc, WaveOne, Twisted File and HyFlex CM systems. Changes in several 2D (area, perimeter, form factor, roundness, minor and major diameter) and 3D [volume, surface area, structure model index (SMI)] morphological parameters, as well as canal transportation, were compared with preoperative values using Kruskal-Wallis and anovapost hoc Tukey's tests with the significance level set at 5%. Preparation significantly increased all tested parameters in the experimental groups. No significant differences were observed between groups regarding changes in volume, surface area, SMI, form factor and roundness of the root canal after preparation (P > 0.05). In the apical third, the Reciproc group had significantly greater changes in canal area, perimeter, major and minor diameters than the other groups (P File and HyFlex CM systems were associated with significantly less transportation than the reciprocating instruments, Reciproc and WaveOne (P File and HyFlex CM systems were able to maintain the original canal anatomy with less canal transportation than Reciproc and WaveOne; however, these differences are unlikely to be of clinical significance. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

3D micro-optical elements for generation of tightly focused vortex beams

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Balčytis Armandas

2015-01-01

Full Text Available Orbital angular momentum carrying light beams are usedfor optical trapping and manipulation. This emerging trend provides new challenges involving device miniaturization for improved performance and enhanced functionality at the microscale. Here we discus a new fabrication method based on combining the additive 3D structuring capability laser photopolymerization and the substractive sub-wavelength resolution patterning of focused ion beam lithography to produce micro-optical elements capable of compound functionality. As a case in point of this approach binary spiral zone pattern based high numerical aperture micro-lenses capable of generating topological charge carrying tightly focused vortex beams in a single wavefront transformation step are presented. The devices were modelled using finite-difference time-domain simulations, and the theoretical predictions were verified by optically characterizing the propagation properties of light transmitted through the fabricated structures. The resulting devices had focal lengths close to the predicted values of f = 18 µm and f = 13 µm as well as topological charge ℓ dependent vortex focal spot sizes of ~ 1:3 µm and ~ 2:0 µm for ℓ = 1 and ℓ = 2 respectively.

Micro-CT evaluation of the effectiveness of the combined use of rotary and hand instrumentation in removal of Resilon.

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Asheibi, Fatma; Qualtrough, Alison J E; Mellor, Anthony; Withers, Philip J; Lowe, Tristan

2014-01-01

This study compares the effectiveness of ProTaper rotary files with ProTaper retreatment and K-files in the removal of Resilon or gutta percha (GP) from canals filled either by cold lateral condensation or thermal obturation using micro-CT. Ninety-six teeth were prepared using ProTaper files and allocated into four groups (n=24): Group-1 was filled with GP/AH-Plus and Group-2 with Resilon/RealSeal using cold lateral condensation. Group-3 was filled with GP/AH-Plus and Group-4 with Resilon/RealSeal using System B and Obtura II. The roots were scanned by micro-CT. Each group was divided into two subgroups (n=12): A, retreated using ProTaper files and B, using ProTaper retreatment and K-files. The roots were scanned to calculate the volume of the remaining material. With thermal obturation, roots filled with Resilon had significantly more remaining material than GP. Obturation using thermal technique resulted in significantly less remaining material than cold condensation except Resilon retreated using ProTaper retreatment and K-files.

Task-driven image acquisition and reconstruction in cone-beam CT

International Nuclear Information System (INIS)

Gang, Grace J; Stayman, J Webster; Siewerdsen, Jeffrey H; Ehtiati, Tina

2015-01-01

This work introduces a task-driven imaging framework that incorporates a mathematical definition of the imaging task, a model of the imaging system, and a patient-specific anatomical model to prospectively design image acquisition and reconstruction techniques to optimize task performance. The framework is applied to joint optimization of tube current modulation, view-dependent reconstruction kernel, and orbital tilt in cone-beam CT. The system model considers a cone-beam CT system incorporating a flat-panel detector and 3D filtered backprojection and accurately describes the spatially varying noise and resolution over a wide range of imaging parameters in the presence of a realistic anatomical model. Task-based detectability index (d′) is incorporated as the objective function in a task-driven optimization of image acquisition and reconstruction techniques. The orbital tilt was optimized through an exhaustive search across tilt angles ranging ±30°. For each tilt angle, the view-dependent tube current and reconstruction kernel (i.e. the modulation profiles) that maximized detectability were identified via an alternating optimization. The task-driven approach was compared with conventional unmodulated and automatic exposure control (AEC) strategies for a variety of imaging tasks and anthropomorphic phantoms. The task-driven strategy outperformed the unmodulated and AEC cases for all tasks. For example, d′ for a sphere detection task in a head phantom was improved by 30% compared to the unmodulated case by using smoother kernels for noisy views and distributing mAs across less noisy views (at fixed total mAs) in a manner that was beneficial to task performance. Similarly for detection of a line-pair pattern, the task-driven approach increased d′ by 80% compared to no modulation by means of view-dependent mA and kernel selection that yields modulation transfer function and noise-power spectrum optimal to the task. Optimization of orbital tilt identified the

Non-destructive test for irradiated fuels using X-ray CT system in hot-laboratory

International Nuclear Information System (INIS)

Kim, Heemoon; Kim, Gil-Soo; Yoo, Boung-Ok; Tahk, Young-Wook; Cho, Moon-Sung; Ahn, Sang-Bok

2015-01-01

To inspect inside of irradiated fuel rod for PIE in hotcell, neutron beam and X-ray have been used. Many hot laboratories in the world have shown the results for NDT by 2-D film data. Currently, computed image processing technology instead of film has been developed and CT was applied to the X-ray and neutron beam system. In this trend, our facility needed to set up X-ray system for irradiated fuel inspection and installed in hotcell with consideration of radiation damage. In this study, X-ray system was tested to be operated with radioactive samples and was performed to inspect fuel rods and observe internal damage and dimensional change. 450kV X-ray CT system was installed in hotcell with modification and tested to check image resolution and radiation damage. The image data were analyzed by 3-D computer software. 8 fuel plates and VHTR rods were inspected and measured internal shape and dimension

Synchrotron μCT imaging of bone, titanium implants and bone substitutes - a systematic review of the literature.

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Neldam, Camilla Albeck; Pinholt, Else Marie

2014-09-01

Today X-ray micro computer tomography (μCT) imaging is used to investigate bone microarchitecture. μCT imaging is obtained by polychromatic X-ray beams, resulting in images with beam hardening artifacts, resolution levels at 10 μm, geometrical blurring, and lack of contrasts. When μCT is coupled to synchrotron sources (SRμCT) a spatial resolution up to one tenth of a μm may be achieved. A review of the literature concerning SRμCT was performed to investigate its usability and its strength in visualizing fine bone structures, vessels, and microarchitecture of bone. Although mainly limited to in vitro examinations, SRμCT is considered as a gold standard to image trabecular bone microarchitecture since it is possible in a 3D manner to visualize fine structural elements within mineralized tissue such as osteon boundaries, rods and plates structures, cement lines, and differences in mineralization. Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Evaluation of patient dose in imaging using a cone-beam CT dosimetry by X-ray films for radiotherapeutic dose

International Nuclear Information System (INIS)

Yoshida, Yuri; Morita, Yasuhiko; Honda, Eiichi; Tomotake, Yoritoki; Ichikawa, Tetsuo

2008-01-01

A limited cone-beam X-ray CT (3DX multi-image micro CT; 3DX-FPD) is widely used in dentistry because it provides a lower cost, smaller size, and higher spatial resolution than a CT for medicine. Our recent research suggested that the patient dose of 3DX-FPD was less than 7/10 of that of CT, and it was several to 10 times more than that of dental or panoramic radiography. The purpose of this study was to evaluate the spatial dose distribution from 3DX-FPD and to estimate the influence of dose by positioning of the region of interest. Dosimetry of the organs and the tissues was performed using an anthropomorphic Alderson Rando phantom and X-ray films for measurement of radiotherapeutic dose. Measurements of dose distribution were performed using a cylinder-type tank of water made of acrylic resin imitating the head and X-ray films. The results are summarized as follows: The dose was higher as the ratio of the air region included in the region of interest increased. The dose distribution was not homogeneous and the dose was highest in the skin region. The dose was higher for several seconds after the beginning of exposure. It was concluded that patient positioning, as well as exposure conditions including the size of the exposure field and tube current, could greatly influence the patient dose in 3DX-FPD. In addition, it is necessary to consider the influence of image quality for the treatment of dental implants. (author)

A Look from the Inside: MicroCT Analysis of Burned Bones

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Francesco Boschin

2015-12-01

Full Text Available MicroCT imaging is increasingly used in paleoanthropological and zooarchaeological research to analyse the internal microstructure of bone, replacing comparatively invasive and destructive methods. Consequently the analytical potential of this relatively new 3D imaging technology can be enhanced by developing discipline specific protocols for archaeological analysis. Here we examine how the microstructure of mammal bone changes after burning and explore if X-ray computed microtomography (microCT can be used to obtain reliable information from burned specimens. We subjected domestic pig, roe deer, and red fox bones to burning at different temperatures and for different periods using an oven and an open fire. We observed significant changes in the three-dimensional microstructure of trabecular bone, suggesting that biomechanical studies or other analyses (for instance, determination of age-at-death can be compromised by burning. In addition, bone subjected to very high temperatures (600°C or more became cracked, posing challenges for quantifying characteristics of bone microstructure. Specimens burned at 600°C or greater temperatures, exhibit a characteristic criss-cross cracking pattern concentrated in the cortical region of the epiphyses. This feature, which can be readily observed on the surface of whole bone, could help the identification of heavily burned specimens that are small fragments, where color and surface texture are altered by diagenesis or weathering.

Non-rigid CT/CBCT to CBCT registration for online external beam radiotherapy guidance

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Zachiu, Cornel; de Senneville, Baudouin Denis; Tijssen, Rob H. N.; Kotte, Alexis N. T. J.; Houweling, Antonetta C.; Kerkmeijer, Linda G. W.; Lagendijk, Jan J. W.; Moonen, Chrit T. W.; Ries, Mario