Purpose: With increasing cone angle the cone– beam artifacts in x–ray CT become more and more prominent. It is well known that cone–beam CT (CBCT) does not satisfy the data completeness condition for exact image reconstruction and therefore allows only for approximate image reconstruction [1]. Additionally, in clinical C–arm CT often only a short scan with less than a full rotation can be acqui...

In CT, the nonlinear attenuation characteristics of polychromatic X-rays cause beam hardening artifacts in the reconstructed images. Statistical algorithms can effectively correct beam hardening artifacts while providing the benefit of noise reduction. In practice, a big challenge for CT is the difficulty at acquiring accurate energy spectrum information, which hinders the efficiency of beam ha...

A table-top volumetric CT system has been implemented that is able to image a 5-cm-thick volume in one circular scan with no cone-beam artifacts. The prototype inverse-geometry CT (IGCT) scanner consists of a large-area, scanned x-ray source and a detector array that is smaller in the transverse direction. The IGCT geometry provides sufficient volumetric sampling because the source and detector...

In the past few years, there has been an increasing interest of the radiation oncology community in cone-beam computed tomography (CT) scanners integrated into the gantry of medical linear accelerators. This imaging device allows to acquire CT images of the patient in treatment position. Unfortunately, like for other CT scanners, the respiratory motion of the patient during acquisition causes a...

BACKGROUND Shape of the dental root canal is highly patient specific. Automated identification methods of the medial line of dental root canals and the reproduction of their 3D shape can be beneficial for planning endodontic interventions as severely curved root canals or multi-rooted teeth may pose treatment challenges. Accurate shape information of the root canals may also be used by manufact...

3.3 Multi-slice CT Acquisition and Reconstruction for Body Imaging 52 3.3.1 Defi nition of the Pitch 52 3.3.2 The Cone-Angle Problem in Multi-slice CT 53 3.3.3 Multi-slice Spiral Reconstruction Neglecting the Cone-Beam Geometry 54 3.3.3.1 180° and 360° Multi-slice Linear Interpolation 54 3.3.3.2 z-Filter Approaches 56 3.3.4 Multi-slice Spiral Reconstruction with Cone-Beam Algorithms 58 3.3.4.1 ...

Ashok Balasundaram: Cone beam Computed Tomography imaging of periodontal bone (Under the direction of Dr. André Mol) Cone beam computed tomography (CBCT) is a low-dose, low-cost three dimensional imaging modality used for several oral and maxillofacial applications. This project evaluated the accuracy of Cone-Beam CT imaging to assess periodontal alveolar bone. In Phase I, ground truth measurem...

In non-destructive testing, computed tomography (CT) is increasingly used for dimensional measurement tasks such as the industrial inspection of work pieces. Besides the determination of the measurement uncertainty, the improvement of the image quality is subject of current research, in order to establish CT as a measuring device. 1. Cone-Beam CT and Metrology Dimensional measurement with CT ha...

AIM To present a newly developed cone beam computerized tomography system (3DX Micro-CT) and its application in endodontic surgery. SUMMARY Cone beam CT has attracted considerable attention as a new diagnostic imaging technique in dentistry. The assessment of fractured endodontic instruments and the planning of endodontic surgery present challenges that conventional radiography cannot meet su...

Background: In CT systems, the machine utilizes a bowtie filter to shape the X-ray beam and remove lower energy photons. The shape of this bowtie filter is complicated and its geometry is often not available in detail. These renders the CT dose index (CTDI) to have different values in measurement versus Monte Carlo simulation studies and other analytical calculations especially in dosimetry of ...