Linear X-ray Detector Arrays Research Articles

Tetrahedron beam computed tomography (TBCT): a new design of volumetric CT system

Volumetric CT imaging systems usually comprise a point x-ray source and a 2D detector. Flat panel imager (FPI)-based cone beam CT (CBCT) has become an important online imaging modality for image-guided radiotherapy and intervention. However, due to excessive scatter photons and inferior detector performance, the image quality of current CBCT is significantly inferior to diagnostic fan-beam CT. We propose a novel tetrahedron beam computed tomography (TBCT) imaging system which consists of a linear scan x-ray source and a linear x-ray detector array. The linear x-ray tube and detector array are aligned perpendicular and parallel to the rotation plane, respectively. The x-ray beams are narrowly collimated into fan beams and focused on the linear detector array. The linear detector and linear x-ray source form a ‘tetrahedron’ volume instead of a ‘cone’ volume. TBCT is similar to CBCT in image reconstruction geometry; however, its image quality will be significantly superior to that of CBCT due to its scatter rejection mechanism and the use of high-performance discrete x-ray detectors. In this paper, we describe the design of the TBCT system for image-guided radiotherapy and some results of preliminary studies.

View synthesis for depth from motion 3D X-ray imaging

The university team has previously developed an X-ray imaging technique that combines binocular stereoscopic imagery with motion or kinetic depth effects. The technique is designed to enhance the screening of X-ray luggage at airport checkpoints. Multiple views are produced using linear or folded linear X-ray detector arrays. The possibility of reducing the total number of arrays by synthesising intermediary views is investigated. The algorithmic approach employs eight correlation criteria which are relaxed during an iterative process. The fidelity of the synthetic images is established by comparing them with ground truth images. It is demonstrated that for each group of three arrays (in a 15 view system) a synthetic image may be employed to make the middle array redundant. This potential reduction in hardware offers important advantages for the development of a practical multiple view X-ray scanner. Limitations of the current algorithm are investigated by increasing the angular separation between the X-ray beams used to produce the perspective images.

Dynamic stereoscopic X-ray imaging

Abstract A multiple view binocular stereoscopic X-ray imaging technique developed as a part of a feasibility study for a security screening application is presented. The experimental system utilises a single X-ray source and a multiple view line-scan camera incorporating an X-ray image intensifier. This set up is used to simulate coplanar configurations of discrete linear X-ray detector arrays. A number of perspective images (typically 6–16) are produced during a single linear translation of the object under inspection. A sequential display of the images produces linear motion parallax in the display. Further work enabled motion parallax to be combined with binocular parallax [NDT&E Int 29 (1996) 27] to produce dynamic binocular stereoscopic images. The perspective images may also be used for the extraction of three-dimensional coordinate information. The results produced by an experimental system are presented together with a theoretical discussion.

Design of a stereoscopic X-ray imaging system using a single X-ray source

The design of a prototype binocular stereoscopic X-ray imaging system for a security screening application is presented. This is based on an innovative technique [Evans JPO, Robinson M, Godber SX. A new stereoscopic imaging technique using a single X-ray source: theoretical analysis. NDT&E International 1996;29(1):27–35] utilising a single X-ray source and a pair of linear X-ray detector arrays. The image data is collected whilst the object under inspection is linearly translated past the X-ray detectors. The machine constructed enables approximately one cubic metre of object space to be imaged in five seconds. The resultant images may also be used for the extraction of three-dimensional coordinate information.

A new stereoscopic X-ray imaging technique using a single X-ray source: theoretical analysis

A binocular stereoscopic X-ray imaging technique is presented which can be used for both visual inspection by human observers and also for the extraction of three-dimensional coordinate information. The concept of implementing a stereoscopic X-ray imaging system to solve the problem of image interpretation is not new in itself. However, what is innovative in this research is the stereoscopic imaging technique developed. This is based on a rigorous design theory specifically developed for a single X-ray source and a pair of linear X-ray detector arrays.

Dimensional reproduction in direct digital rotational panoramic radiography

A linear x-ray detector array can be used to perform rotational panoramic radiography provided a technique for data acquisition is used that emulates the dimensional reproduction of a conventional rotational panoramic radiographic system. This may be accomplished with the use of a variable integration time throughout the excursion. The required interval depends upon the scanning geometry, the selected image plane, and the size of pixels used in the digital image. In a prototype device developed around an Orthopantomograph Model OP10 with 0.225 mm square pixels, the integration times range from about 8 milliseconds to 28 milliseconds. An experimental test was performed by radiographing a number of steel spheres positioned at different object depths. Within the limits of experimental error, there was satisfactory agreement between the measured and theoretical magnification.