Real-time Radiographic Imaging Research Articles

Clinical Implementation and Initial Experience of Real-Time Motion Tracking With Jaws and Multileaf Collimator During Helical Tomotherapy Delivery

PurposeThis work reports the clinical implementation of a real-time motion tracking and correction system using dynamic multileaf collimator and jaws during helical tomotherapy delivery (Synchrony on Radixact; Accuray, Inc). Methods and MaterialsThe first clinical Synchrony on Radixact system was recently installed and tested at our institution. Various clinical workflows, including fiducial implantation, computed tomography simulation, treatment planning, delivery quality assurance, treatment simulation, and delivery, for both fiducial-free and fiducial-based motion tracking methods were developed. Treatment planning and delivery data from initial patients, including dosimetric benefits, real-time target detection, model building, motion tracking accuracy, delivery smoothness, and extra dose from real-time radiographic imaging, were analyzed. ResultsThe Synchrony on Radixact system was tested to be within its performance specifications and has been used to treat 10 lung (fiducial-free) and 5 prostate (fiducial-based) patients with cancer so far in our clinic. The success of these treatments, especially for fiducial-free tracking, depends on multiple factors, including careful selection of the patient, appropriate setting of system parameters, appropriate positioning of the patient and skin markers, and use of treatment simulation. For the lung tumor cases, difficulties in model building, due primarily to the changes of target detectability or respiration patterns, were observed, which led to important system upgrades, including the addition of a treatment delivery simulation capability. Motion tracking metrics for all treated patients were within specifications, for example, (1) delivery quality assurance passing rates >95%; (2) extra dose from radiograph <0.5% of the prescription dose; and (3) average Potential Diff, measured Δ, and Rigid Body were within 6.5, 2.9, and 3.9 mm, respectively. ConclusionsPractical workflows for the use of the first clinical motion tracking and correction system in helical tomotherapy delivery have been developed, and the system has now been successfully implemented in our clinic for treating patients with lung and prostate cancer.

Development of low-cost industrial x-ray computed tomography system based on digital fluoroscopy

Computed tomography (CT) offers an effective method of non-destructive testing for quality control in the manufacturing of complex parts. Using CT allows examination any internal anomaly of a sample like a defect, internal porosity, void detection, and cracks. However commercial X-ray CT equipment on markets is expensive. So it is required to develop low-cost X-ray CT equipment that provides good image quality and fast scanning. This paper describes the development of digital fluoroscopy-based X-ray CT system. It consists of an X-ray source, a rotary table system, a digital fluoroscopy detector, and a computer. This research uses a fluorescent screen to make the X-ray image visible which then digitized by a CMOS camera. The real-time radiographic image can be visualized and interpreted using a computer. These advantages make acquisition time for scanning images is reduced to only a few seconds. This equipment is relatively cheaper than the same system used in industry. It has been tested with an object of an aluminum step wedge cylinder by scanning 361 images, which were then reconstructed using the Octopus Reconstruction 8.9 software with a filtered back-projection method. The resulting image quality is quite good as it is easily interpreted by the user’s eyesight. The implication of this research is the possibility of producing a low-cost X-ray CT equipment made within the country.

Automatic weld defect detection based on potential defect tracking in real-time radiographic image sequence

An effective and adaptive method is proposed to automatically detect weld defects using defect tracking in real-time radiographic image sequence of a moving weld. Firstly, a defect segmentation algorithm with low threshold is used to segment all of the potential weld defects in each image of the sequence. Then the modified Hough transform is employed to track the center of gravity of potential defects in image sequence, and the potential defects that cannot be tracked are eliminated as false defects. Experiment results show that the proposed method can detect weld defects with high certainty and avoid false alarms caused by the noise.

What technical barriers exist for real‐time fluoroscopic and video image overlay in robotic surgery?

A hypothetical advantage of the da Vinci console is its ability to integrate multiple visual data sources. Current platforms for augmented reality surgery fuse pre-operative radiographic studies but are limited with their ability to update with intra-operative imaging. The aim of our study was to evaluate the feasibility of real-time radiographic image overlay with current technology. S-video composite output from a fluoroscopic C-arm was superimposed onto the video output of the da Vinci device. Image superimposition disparity measurements were evaluated in a bench model. The feasibility of robotic dissection assisted by real-time cholangiogram and intravenous pyelogram was evaluated. Image alignment resulted in a radiographic blind spot and image disparity with severely limited application in an in vivo model. External collisions of the robotic device and visual disparity in multiple planes negate the current implementation of fluoroscopic overlay and will require more elegant methods of computer-assisted registration.

Nondestructive analysis of fiber dispersion and loading

This paper discusses a new nondestructive method of characterizing both the quality of fiber dispersion and the amount of fiber loading for injection-molded, glass-reinforced nylon. The technique is based on real-time radiographic imaging, and it uses image processing to obtain the results more quickly than current methods. The technique works well for a variety of two-phase systems, including those with a non-fibrous reinforcing phase. Theory and protocol for this new method are presented, and experimental results are compared with the results of conventional loading measurements. The quality of dispersion for long discontinuous fibers is observed to improve with decreasing melt viscosity. Mapping of resin poor areas is also possible with this approach.

Characteristics of a novel X-ray detector for real-time radiographic imaging

Abstract New detectors for fast, real-time, high resolution X-ray imaging at high photon fluxes are described. A thin solid photoconverter is coupled to a multistage gaseous electron multiplier operating at low pressure. The readout electronics connected to the wire electrodes of the chamber provides two-dimensional localization of single registered photons. Prototype detectors were tested with Csl, Ag and Ta converters in the photon energy range of 8–60 keV. Radiographic digital images are presented compared to that of X-ray films. It is shown that compared to the film technique the secondary electron emission detector provides radiographic images of an equivalent contrast at an order of magnitude lower exposure. This novel type of detector is suited for static and dynamic in-line quality control on industrial production lines and for medical imaging.

48475 Three-dimensional computed tomography (3-D CT) using realtime radiographic images : 1991 Industrial Computed Tomography II, San Diego, California (United States), 20–24 May 1991. pp. 130–134. ASNT (1991)

48475 Three-dimensional computed tomography (3-D CT) using realtime radiographic images : 1991 Industrial Computed Tomography II, San Diego, California (United States), 20–24 May 1991. pp. 130–134. ASNT (1991)

High resolution computed tomography : Boeing Aerospace and Electronics Co., Seattle, Washington, D.C. (United States), AD-A259 728/4/GAR, 39 pp. (31 Jul. 1992)

Abstract : High resolution (greater than 4 line pairs per millimeter) computed tomography (CT) has been studied for its potential use for engineering evaluation of aerospace components. The CT images provide two dimensional maps of material linear x-ray attenuation coefficients for small volume elements, smaller than 0.001 cubic millimeters. These images are similar to micrographic images of polished surfaces from sectioned components, but are achieved nondestructively. For investigating materials where destructive sectioning relieves stresses, changing the internal configuration of features, such as gaps, high resolution CT provides superior diagnostic information for engineering evaluation. The primary benefits of CT are realized in accelerating schedules through faster data acquisition and reducing engineering risk by providing increased information nondestructively. High resolution CT is particularly well suited to assist in failure analysis investigations. Multiple slice or volume reconstruction high resolution CT can provide full three dimensional models. The cost and performance of high resolution CT systems are functions of the component size and ultimate resolution capability. For many common evaluation needs, the capital cost can be as low as a 50 percent cost add-on to a real-time radiographic imaging system. Relative to micrography, CT can be performed in about on-fifth the time, depending on the number of samples.

Computed neutron tomography from real-time radiographic images : 37872 Sulcoski, M.F.; Brenizer, J.S. Neutron Radiography, Proceedings of the Second World Conference, Paris (France), 16–20 Jun. 1986. pp. 753–760. D. Reidel Publishing Company

Computed neutron tomography from real-time radiographic images : 37872 Sulcoski, M.F.; Brenizer, J.S. Neutron Radiography, Proceedings of the Second World Conference, Paris (France), 16–20 Jun. 1986. pp. 753–760. D. Reidel Publishing Company

Computed neutron tomography from real-time radiographic images : Sulcoski, M.F.; Brenizer, J.S. neutron radiography, proceedings of the second world conference, Paris (France), 16–20 Jun. 1986. pp. 753–760. D. Reidel Publishing Company

Computed neutron tomography from real-time radiographic images : Sulcoski, M.F.; Brenizer, J.S. neutron radiography, proceedings of the second world conference, Paris (France), 16–20 Jun. 1986. pp. 753–760. D. Reidel Publishing Company

Quick methods of supervising microfocal X-ray sources for real time radiographic image : Notea, A.; Pal, D.; Deutsch, M. Proceedings of the 4th European conference on non-destructive testing, London (United Kingdom), 13–17 Sep. 1987. Vol. 3 pp. 2093–2102. Pergamon Press, 3173 pp. (1988)

Quick methods of supervising microfocal X-ray sources for real time radiographic image : Notea, A.; Pal, D.; Deutsch, M. Proceedings of the 4th European conference on non-destructive testing, London (United Kingdom), 13–17 Sep. 1987. Vol. 3 pp. 2093–2102. Pergamon Press, 3173 pp. (1988)

Slit design considerations for rotating-aperture, scanning-beam radiography.

The rotating-aperture wheel (RAW) scanning-beam device is uniquely applicable for scatter elimination in short-time, rapid-sequence, and real-time radiographic imaging because of the continuous rotary motion of its slit pattern. This rotary motion places special restrictions on the slit pattern design. Although simple sector-shaped slits provide uniform primary transmission, they entail an unacceptable degree of slit widening on small-diameter wheels. The use of multiple slit zones with slits of different angular width has reduced the extent of this widening on a prototype RAW; however, interzone boundary artifacts caused by differential primary x-ray cutoff are apparent on some clinical images. This problem is eliminated with a unique spiral-shaped aperture pattern which consists of slits of constant width and constant spacing. Each slit is radially continuous and provides uniform primary transmission without interzone artifacts. This spiral pattern satisfies all requirements and appears to be the pattern of choice for rotating-aperture scanning-beam radiography.

An evaluation of a fluorescent screen-isocon camera system for x-ray imaging in radiology.

A large field format imaging system which utilizes a flat fluorescent screen rather than the traditional image intensifier as the primary x-ray detector is discussed in this paper. A low light level image isocon camera is optically coupled to a rare-earth screen. An overview of the isocon camera and its return beam mode of operation is included. Theoretical limitations to this approach to real time radiographic imaging are discussed in terms of system efficiency and signal-to-noise ratio (SNR) requirements. The viability of this concept for radiographic imaging is considered with respect to the image intensifier-camera unit. The merits of employing a CsI:Na screen as the primary detector and an isocon tube with an improved SNR are presented as potential areas for further investigation.