Three-dimensional Imaging Technology Research Articles

Modeling of structure, quality, and function in the orthodontic patient.

The advantages of three-dimensional (3-D) imaging technology and solid modeling make it possible to visualize the morphological information. However, lacking in this 'digital patient' is the motion and mechanical properties observed in the living patient. Functional diagnostic techniques such as electromyography and motion analysis could complement the morphological characteristics to be applied in orthodontics. In this review, new computer-assisted analyzing methods are introduced which include visualization of: 1) the 3-D structure and bone density distribution; 2) masticatory-generated forces by using automated finite element modeling (FEM); and 3) the 3-D jaw movement and its motion analysis. In each study, the data from X-ray computed tomography scanning, electromyograms, biting pressure, and digital jaw movement analysis (six axes) are used for calculation. By using these applications, growing changes in bone mineral density distribution of the mandibular cortical bone have been clarified, automated finite element modeling has indicated stress distribution in the craniofacial skeleton, and patient-specific 3-D images of the mandible have been depicted as a motion picture. These studies were completed in 124 living subjects (75 females, 49 males) between 8 and 33 years of age. From these results, malfunctions during mastication were evaluated clearly with the individual patient craniofacial structures and its characteristics. These computer-based visualization techniques can be used to derive much clinically useful information, and to improve the combined evaluation of both static characteristics and dynamic function.

Soft x-ray holographic computerized tomography imaging: experimental research.

A high-resolution three-dimensional (3D) imaging technology has been developed, which is a combination of x-ray holography and computerized tomography (CT) technology called holographic computerized tomography (HCT). The theory and experimental techniques on biological specimens with the use of synchrotron radiation are discussed. Projections at different angles are reconstructed with the numerical method of in-line holography, and then the reconstructed data with a higher lateral resolution are used to restore the 3D image by the CT technique. With this method, the degradation caused by the diffraction of x rays is canceled, and 3D images with high resolution of micrometer magnitude in both the lateral and the longitudinal directions are obtained.

Three-dimensional video-assisted thoracoscopic pericardiectomy

Video-assisted thoracic surgery has proven to be safe and effective for the diagnosis and management of pericardial disease. Three-dimensional (3-D) video imaging technology has been developed to allow the laparoscopic surgeon more precision and efficiency in advanced laparoscopic cases. This case report describes the marriage of 3-D video imaging and thoracoscopy that allowed performance of a technically difficult pericardiectomy without incident. Our aim is to describe the use of state-of-the-art 3-D video imaging to allow success in difficult cases.

A review of high-resolution seismic profiling across the Sudbury, Selbaie, Noranda, and Matagami mining camps

Lithoprobe high-resolution seismic surveys have provided the first systematic images of the deep stratigraphy in four major Canadian mining camps (Noranda, Matagami, Sudbury, and Selbaie). Systematic compressional wave velocity and density measurements in deep boreholes have established that lithological contacts were the main impedance contrast imaged, although reflections from faults and deformation zones have also been observed. The strongest reflections are attributed to mafic intrusions and some sulphides and oxides. Integrating seismic, physical rock property measurements, and geological data has resulted in the revision of several geological models with direct impact on local strategies for deep mineral exploration. Mining companies have shown an interest in seismic reflection methods and this has led to several follow-up studies. The application of seismic methods to the direct detection of massive sulphides, based on physical rock property measurements, has been studied through two-dimensional and three-dimensional (3D) seismic imaging and vertical seismic profiling technologies. The challenge will now be to optimize 3D seismic imaging for mineral exploration and to improve seismic data processing by enhancing the seismic response from deep, lenticular orebodies.

Virtual Endoscopy: Application of 3D Visualization to Medical Diagnosis

Virtual endoscopy is a diagnostic technique in which a three-dimensional imaging technology (CT scan, MRI scan, ultrasound) is used to create a computer-generated representation of a specific patient's anatomy or organ, and then the virtual organ is “flown through,” giving the same visual impression and image as if the corresponding real organ had a video or fiberoptic endoscopic procedure performed. The potential is to provide a computer diagnosis to replace an endoscopic procedure, not only for conventional endoscopy such as bronchoscopy, colonoscopy, sinusoscopy, or hysteroscopy, but also for areas where traditional endoscopy is not possible, such as the inner ear, spleen, lymphatic tissues. With sophisticated signal processing and computational analysis, it may be possible in the future to perform a “numerical biopsy,” that is, make a tissue diagnosis based upon spectral or other information contained in the images.

Preliminary clinical outcome and imaging criterion for endovascular prosthesis development in high-risk patients who have aortoiliac and traumatic arterial lesions.

This report reviews our preliminary experience of prospective treatment of arterial lesions with endoluminal grafts in a Food and Drug Administration (FDA)-approved, investigator-sponsored Investigation Device Exemptions study. The utility and accuracy of various imaging methods, including angiography, cinefluoroscopy, computed tomography (CT), intravascular ultrasonography (IVUS), and duplex scanning, in performing the procedures was also assessed. Thirty-one patients were evaluated; 17 patients were treated, including 11 with abdominal aortic aneurysms, one with an aortic occlusive lesion, two with iliac artery aneurysms, and three with traumatic arteriovenous fistulas. Twelve of the 14 patients who had aorta and iliac artery lesions were high-risk. The mean follow-up of patients treated was 9 months (range, 6 to 15 months). Aortoaortic endoluminal interposition procedures were not successful for treating abdominal aortic aneurysms early in the study (n = 3). Aortoiliac endoluminal bypass, contralateral iliac artery occlusion, and femorofemoral bypass procedures were successful in seven of eight subsequent cases (88%), with no incidence of endoleaks at either the proximal or distal fixation sites using the deployment methods described in this report. The 30-day operative mortality rate on follow-up evaluations for patients who underwent aortoiliac procedures was 14% (two of 14). Other major complications included transient renal failure in three patients that required short-term (two to eight times) dialysis, one arterial perforation and one dissection, and one prolonged intubation. No myocardial infarctions or strokes occurred. After major complications or identification of limitations in the study, the protocol was modified with the approval of the FDA to help avoid the recurrence of the same problems. There were no deaths or complications in the trauma cases. Contrast-enhanced CT (axial images and spiral reconstructions) was the most accurate method to determine candidacy for aortoiliac procedures and to choose the site for deployment of the devices. Angiographic scans were misleading in several patients regarding the critical determinants of patient candidacy and device deployment, particularly regarding the presence of a distal aortic neck. Cinefluoroscopy was used in all patient and was particularly useful for determining the continuity of vascular structures and the anatomy of branch arteries and for enabling precise positioning of stent devices. Determination of fixation sites and assessing dimensional information by cinefluoroscopy and angiography were limited by inaccuracies produced by image magnification, parallax, and uniplanar views. IVUS was used to determine the morphologic features of vascular structures (i.e., calcium, thrombus), to perform real-time observation of the expansion of devices, and to assure firm fixation of balloon-expanded stents before the procedures were completed. Duplex scanning was very helpful in assessing and identifying precisely the location of arteriovenous fistulas before intervention and provided assessment at follow-up intervals. Three-dimensional reconstruction imaging technologies such as spiral CT were particularly helpful for assessing the morphologic features of vascular anatomy before the intervention and at follow-up intervals, whereas 3-D IVUS provided a similar real-time perspective during the procedure.

Multifrequency studies of bright radio supernova remnants. 2: W49B

view Abstract Citations (55) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Multifrequency Studies of Bright Radio Supernova Remnants. II. W49B Moffett, David A. ; Reynolds, Stephen P. Abstract We report radio observations of the supernova remnant W49B using the Very Large Array (VLA) of the NRAO at 90, 20, and 6 cm. This work continues the study of the properties of young, bright supernova remnants (SNRs) begun with 3C 391 (Moffett & Reynolds 1994). Here we present high-resolution images of total intensity, polarization, and spectral index of W49B. In large-scale morphology it is basically a box-shaped remnant expanding into an apparently inhomogeneous medium, but we also find small-scale structures, arcs and filaments, which lie interior to the outer shell in projection. The actual spatial position of the filaments is unknown, though we suspect that they are in the remnant interior rather than on the front or back face of the blast wave. In addition, their distribution in two dimensions suggests the projection of a helical structure. The shell edge, sharply rising in brightness for at least 3/4 of its circumference, still remains unresolved at our highest resolution (4 sec). This for our assumed distance of 8 kpc, the width of the region in which the emission appears is less than 0.16 pc, indicating short mean free paths for shock-accelerated electrons and high levels of MHD turbulence presumably causing the scattering. We find no polarized flux at 90 or 20 cm, with 3 sigma upper limits in polarized intensity of 36 mJy at 90 cm (45 sec resolution) and 7.2 mJy at 20 cm (5 sec resolution), or 22 micro-Jy/sq arcsec and 370 micro-jy/sq arcsec, respectively, for any emission extended on those scales. Polarized flux is present at 6 cm, but at a very low mean polarized fraction (total polarized flux divided by total flux) of 0.44% +/- 0.06%, which, as for 3C 391, is much lower than typical for bright SNRs at this frequency. The morphology in polarized intensity is poorly correlated with that in total intensity. We see excursions in the polarized fraction up to at least 10% in a few locations, but even where polarization is seen, typical levels are a few percent. Tangled or disordered magnetic fields in the emitting region of the radio shell may be responsible for depolarizing the radio synchrotron radiation, but some form of internal Faraday depolarization may also occur. We estimate the foreground Faraday rotation measure to be about -450 rad/sq m, similar to that found for 3C 391, which is also the Galactic plane and just about as distant. Spectral index images created from the total intensity images show that the spectral index across W49B is constant to within about Delta alpha approximately 0.1 in bright regions. This result weakly supports a common origin of the radio-emitting electrons, as in the blast wave, rather than in inhomogeneous turbulent regions of differing properties due to the stochastic (second-order Fermi) acceleration process. Variations at the level of Delta alpha approximately 0.1 are seen, but their significance is doubtful. New observations at 90 cm, using experimental three-dimensional imaging technology, may improve on this limit. Publication: The Astrophysical Journal Pub Date: December 1994 DOI: 10.1086/175033 Bibcode: 1994ApJ...437..705M Keywords: High Energy Electrons; Interstellar Matter; Magnetohydrodynamic Turbulence; Polarization; Polarized Electromagnetic Radiation; Radio Astronomy; Radio Observation; Supernova Remnants; Synchrotron Radiation; Faraday Effect; Morphology; Radio Sources (Astronomy); Radio Telescopes; Shock Waves; Very Large Array (Vla); Astronomy; ISM: INDIVIDUAL ALPHANUMERIC: W49B; POLARIZATION; RADIO CONTINUUM: ISM; ISM: SUPERNOVA REMNANTS full text sources ADS | data products SIMBAD (4) Related Materials (2) Part 1: 1994ApJ...425..668M Part 3: 1999ApJ...526..365D

Multifrequency studies of bright radio supernova remnants. 1: 3C 391

We report radio observations of the supernova remnant W49B using the Very Large Array (VLA) of the NRAO at 90, 20, and 6 cm. This work continues the study of the properties of young, bright supernova remnants (SNRs) begun with 3C 391 (Moffett & Reynolds 1994). Here we present high-resolution images of total intensity, polarization, and spectral index of W49B. In large-scale morphology it is basically a box-shaped remnant expanding into an apparently inhomogeneous medium, but we also find small-scale structures, arcs and filaments, which lie interior to the outer shell in projection. The actual spatial position of the filaments is unknown, though we suspect that they are in the remnant interior rather than on the front or back face of the blast wave. In addition, their distribution in two dimensions suggests the projection of a helical structure. The shell edge, sharply rising in brightness for at least 3/4 of its circumference, still remains unresolved at our highest resolution (4 sec). This for our assumed distance of 8 kpc, the width of the region in which the emission appears is less than 0.16 pc, indicating short mean free paths for shock-accelerated electrons and high levels of MHD turbulence presumably causing the scattering. We find no polarized flux at 90 or 20 cm, with 3 sigma upper limits in polarized intensity of 36 mJy at 90 cm (45 sec resolution) and 7.2 mJy at 20 cm (5 sec resolution), or 22 micro-Jy/sq arcsec and 370 micro-jy/sq arcsec, respectively, for any emission extended on those scales. Polarized flux is present at 6 cm, but at a very low mean polarized fraction (total polarized flux divided by total flux) of 0.44% +/- 0.06%, which, as for 3C 391, is much lower than typical for bright SNRs at this frequency. The morphology in polarized intensity is poorly correlated with that in total intensity. We see excursions in the polarized fraction up to at least 10% in a few locations, but even where polarization is seen, typical levels are a few percent. Tangled or disordered magnetic fields in the emitting region of the radio shell may be responsible for depolarizing the radio synchrotron radiation, but some form of internal Faraday depolarization may also occur. We estimate the foreground Faraday rotation measure to be about -450 rad/sq m, similar to that found for 3C 391, which is also the Galactic plane and just about as distant. Spectral index images created from the total intensity images show that the spectral index across W49B is constant to within about Delta alpha approximately 0.1 in bright regions. This result weakly supports a common origin of the radio-emitting electrons, as in the blast wave, rather than in inhomogeneous turbulent regions of differing properties due to the stochastic (second-order Fermi) acceleration process. Variations at the level of Delta alpha approximately 0.1 are seen, but their significance is doubtful. New observations at 90 cm, using experimental three-dimensional imaging technology, may improve on this limit.

Conformal Radiotherapy at the Royal Marsden Hospital (UK)

Conformal radiotherapy seeks to allow increased intensity of radiation by reducing the volume of normal tissues within the treatment volume. Techniques have developed secondary to improvements in three-dimensional imaging and accessible treatment technology is based on computer-controlled multileaf collimators to create an irregular radiation beam shape. Preliminary clinical work in the Royal Marsden Hospital seeks to quantify the toxicity reduction achievable by conformal techniques in the context of a prospective randomized pelvic radiotherapy trial which has now recruited 240 patients. The data accumulated during this trial will allow comparison of conformal and conventional radiotherapy and also analysis of the impact of dose and volume of a particular organ on both acute and late toxicity. Assessments have revealed that conformal techniques reduced significantly the treatment volume of normal tissues, e.g. by a mean of 54% for rectum and 42% for bladder. However, a relationship between volume and acute toxicity has not been established. Late toxicity is currently being analysed. Dose escalation trials in thoracic and in pelvic tumours are planned.

Custom Footwear: The Role of Computer-Aided Engineering

Abstract We propose that research be performed to specify the computer-aided engineering required in custom footwear production. Presently, custom shoes for orthopedic conditions and for very active athletes must be derived from casts representing foot topography or wood lasts which must be modified by hand to represent the essential biomechanical features. Three-dimensional (3-D) imaging technology should be accessed for application to this problem. In replacing the cast and last skill-based techniques, the proposed system would record surface and underlying bony topographies for display and operator modifications made interactively on the computer screen. Software, like the operator intervention, would introduce biomechanical requirements of pathology or of special service demands, as in sports. Pressure mapping can also be introduced to display how shape modifications affect the critical force (shear) patterns on the foot. Stages are proposed in the development of a complete system for the provision of custom footwear, making such footwear accessible to an increased proportion of the nation's population.