Modeling and Analysis of Soft-Test/Repair for CCD-Based Digital X-Ray Systems

Modern X-ray imaging systems evolve toward digitization for reduced cost, faster time-to-diagnosis, and improved diagnostic confidence. For the digital X-ray systems, charge coupled device (CCD) technology is commonly used to detect and digitize optical X-ray image. This paper presents a novel soft-test/repair approach to overcome the defective pixel problem in CCD-based digital X-ray systems through theoretical modeling and analysis of the test/repair process. There are two possible solutions to cope with the defective pixel problem in CCDs: one is the hard-repair approach and another is the proposed soft-test/repair approach. Hard-repair approach employs a high-yield, expensive reparable CCD to minimize the impact of hard defects on the CCD, which occur in the form of noise propagated through A/D converter to the frame memory. Therefore, less work is needed to filter and correct the image at the end-user level while it maybe exceedingly expensive to practice. On the other hand, the proposed soft-test/repair approach is to detect and tolerate defective pixels at the digitized image level; thereby, it is inexpensive to practice and on-line repair can be done for noninterrupted service. It tests the images to detect the detective pixels and filter noise at the frame memory level and caches them in a flash memory in the controller for future repair. The controller cache keeps accumulating all the noise coordinates and preprocesses the incoming image data from the A/D converter by repairing them. The proposed soft-test/repair approach is particularly devised to facilitate hardware level implementation ultimately for real-time telediagnosis. Parametric simulation results demonstrate the speed and virtual yield enhancement by using the proposed approach; thereby highly reliable, yet inexpensive, soft-test/repair of CCD-based digital X-ray systems can be ultimately realized

BIST Design for CCD Based Digital Imaging System

This paper presents a BIST design for CCD-based digital imaging system. Pixels on a CCD are not free from defective or faulty pixels due to numerous causes such as imperfect fabrication, excessive exposure to light, radiation, sensing element aging, and excessive mechanical shock, to mention a few. Today\u27s high demand for high resolution CCDs is dictating defect/fault-tolerance in such devices. Especially, traditional on-device BIST cannot be readily employed on the imaging devices such as CCD due to the unique requirement that no pixel can be utilized to repair or bypass a defect on any other pixels. Therefore, the BIST technique designed and simulated in this paper is a technique to test and repair the defects on pixels off the device, referred to as off-device tolerance. The basic idea was proposed in our previous work in [2] where the off-device defect/fault tolerance was investigated and a soft-test/repair technique was theoretically proposed in order to demonstrate the efficiency and effectiveness in terms ofreliability, referred to as virtual yield. A Verilog-based design and simulation is provided to demonstrate the validity of the off-device soft-test/repair in terms of reliability (or virtual yield) enhancement and performance

Modeling, Analysis and Design of Reliable Digital Imaging System

Charge Coupled Device (CCD) is one of the most popular imaging sensors such as digital camera, digital camcorders, and digital x-ray diagnosis systems to mention a few. As the need for high resolution and high sensitive CCDs, high yield and solid reliability are becoming critical requirements for CCDs. In this context, soft-test/repair method must be developed to achieve high yield and reliability for CCDs. The purpose of this study was to propose soft-test and repair methods for defective pixels in CCD system, thereby realizing more reliable and cost-effective CCD Systems. Various test/repair algorithms are proposed and verified, and BIST/BISR architecture was proposed and the design was verified through verilog HDL simulation. Extensive parametric simulation results are also shown.Computer Science Departmen

Index to 1984 NASA Tech Briefs, volume 9, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1984 Tech B Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

DYNAMIC MEASUREMENT OF THREE-DIMENSIONAL MOTION FROM SINGLE-PERSPECTIVE TWO-DIMENSIONAL RADIOGRAPHIC PROJECTIONS

The digital evolution of the x-ray imaging modality has spurred the development of numerous clinical and research tools. This work focuses on the design, development, and validation of dynamic radiographic imaging and registration techniques to address two distinct medical applications: tracking during image-guided interventions, and the measurement of musculoskeletal joint kinematics. Fluoroscopy is widely employed to provide intra-procedural image-guidance. However, its planar images provide limited information about the location of surgical tools and targets in three-dimensional space. To address this limitation, registration techniques, which extract three-dimensional tracking and image-guidance information from planar images, were developed and validated in vitro. The ability to accurately measure joint kinematics in vivo is an important tool in studying both normal joint function and pathologies associated with injury and disease, however it still remains a clinical challenge. A technique to measure joint kinematics from single-perspective x-ray projections was developed and validated in vitro, using clinically available radiography equipmen

Two-dimensional reflectivity polarization elastometry imaging techniques (PIET) of soft tissue

A non-invasive polarized light reflection measurement method to measure the stretch of soft tissue, such as skin, is described. The technique utilizes changes in the reflectivity of polarized light intensity as a monitor of skin stretch. Measurements on in-vitro pigskin and invivo human skin show that the reflectivity of polarized light intensity increases linearly with stretch over a range. The changes in diffusive reflectivity properties of skin result from the alterations that take place in the roughness across the thickness of the skin layers due to stretch. Conceptually, as the roughness of a layer decreases with stretch, a smoother reflecting media is produced resulting in a proportional increase in the specular reflection. Results can be easily extended to a real time stretch analysis of large tissue areas that would be applicable for mapping the stretch of skin. Simple one- and two-dimensional sinusoidal theoretical surface roughness model correctly predicts the experimental measurements. In-vitro pigskins were also used for the tissue bum experiments and its measured reflectivity slope versus stretch increases with the bum duration up to a limited thermal excitation. Above this limit, the in-vitro sample becomes optically transparent, as its biomechanical properties is thermally altered and a negative reflectivity slope is observed

Small business innovation research. Abstracts of completed 1987 phase 1 projects

Non-proprietary summaries of Phase 1 Small Business Innovation Research (SBIR) projects supported by NASA in the 1987 program year are given. Work in the areas of aeronautical propulsion, aerodynamics, acoustics, aircraft systems, materials and structures, teleoperators and robotics, computer sciences, information systems, spacecraft systems, spacecraft power supplies, spacecraft propulsion, bioastronautics, satellite communication, and space processing are covered