We show that x-ray computer tomography algorithms can be applied with minimal alteration to the three-dimensional reconstruction of visible sources. Diffraction and opacity affect visible systems more severely than x-ray systems. For camera-based tomography, diffraction can be neglected for objects within the depth of field. We show that, for convex objects, opacity has the effect of windowing ...

Absorption based CT imaging has been an invaluable tool in medical diagnosis, biology, and materials science. However, CT requires a large set of projection data and high radiation dose to achieve superior image quality. In this letter, we report a new imaging modality, X-ray Induced Acoustic Tomography (XACT), which takes advantages of high sensitivity to X-ray absorption and high ultrasonic r...

Radiation dose in x-ray computed tomography (CT) has become a topic of high interest due to the increasing numbers of CT examinations performed worldwide. This review aims to present an overview of current concepts for both scanner output metrics and for patient dosimetry and will comment on their strengths and weaknesses. Controversial issues such as the appropriateness of the CT dose index (C...

Current computed tomography (CT) scanners, including micro-CT scanners, utilize a point x-ray source. As we target higher and higher spatial resolutions, the reduced x-ray focal spot size limits the temporal and contrast resolutions achievable. To overcome this limitation, in this paper we propose to use a line-shaped x-ray source so that many more photons can be generated, given a data acquisi...

With the advent of industrial computed tomography (CT or reconstruction from projections), which is of much wider scope than medical CT, the basic mathematical and physical assumptions need to be reconsidered. This paper considers the ramifications of the indeterminacy theorem and the underdetermined nature of the reconstruction equations. A search for truth rather than honesty in their solutio...

Grating-based x-ray imaging provides three principle kinds of contrast: absorption, phase, and dark-field. Due to the availability of tomographic reconstruction algorithms for the dark-field contrast, it is now possible to take advantage of quantitative scatter information. However, the published algorithm is based on several assumptions that might be violated in reality. We use numerical simul...

Neutrons are sourced from the SAFARI-1 nuclear research reactor operated by Necsa. Necsa is located at Pelindaba in the Northwest Province of South Africa, which is 30 km west of Pretoria. The South African Neutron Radiography (SANRAD) facility is located on the beam port floor of the SAFARI-1 nuclear research reactor hall and sources neutrons from beam port No. 2. The facility has neighbouring...

Phase contrast X-ray tomography (PCT) enables the study of systems consisting of elements with similar atomic numbers. Processing datasets acquired using PCT is nontrivial because of the low-pass characteristics of the commonly used single-image phase retrieval algorithm. In this study, we introduce an image processing methodology that simultaneously utilizes both phase and attenuation componen...

background and aims. at present, cone beam computed tomography (cbct) has become a substitute for computed tomography (ct) in dental procedures. the metallic materials used in dentistry can produce artifacts due to the beam hardening phenomenon. these artifacts decrease the quality of images. in the present study, the number of artifacts as a result of beam hardening in the images of dental imp...

normal 0 false false false en-us x-none ar-sa spinal hematoma is a rare and usually severe neurological disorder that, without adequate treatment, often leads to death or permanent neurological deficit. epidural as well as subdural and subarachnoid hematomas have been investigated in some studies. a 66-year-old man referred to our hospital because of acute onset paraplegia and incontinency star...