Flat-Panel Volume CT: Fundamental Principles, Technology, and Applications (original) (raw)

Ultrahigh resolution flat-panel volume CT: fundamental principles, design architecture, and system characterization

European Radiology, 2006

Digital flat-panel-based volume CT (VCT) represents a unique design capable of ultra-high spatial resolution, direct volumetric imaging, and dynamic CT scanning. This innovation, when fully developed, has the promise of opening a unique window on human anatomy and physiology. For example, the volumetric coverage offered by this technology enables us to observe the perfusion of an entire organ, such as the brain, liver, or kidney, tomographically (e.g., after a transplant or ischemic event). By virtue of its higher resolution, one can directly visualize the trabecular structure of bone. This paper describes the basic design architecture of VCT. Three key technical challenges, viz., scatter correction, dynamic range extension, and temporal resolution improvement, must be addressed for successful implementation of a VCT scanner. How these issues are solved in a VCT prototype and the modifications necessary to enable ultra-high resolution volumetric scanning are described. The fundamental principles of scatter correction and dose reduction are illustrated with the help of an actual prototype. The image quality metrics of this prototype are characterized and compared with a multi-detector CT (MDCT).

Musculoskeletal applications of flat-panel volume CT

Skeletal Radiology, 2008

Flat-panel volume computed tomography (fpVCT) is a recent development in imaging. We discuss some of the musculoskeletal applications of a high-resolution flat-panel CT scanner. FpVCT has four main advantages over conventional multidetector computed tomography (MDCT): high-resolution imaging; volumetric coverage; dynamic imaging; omni-scanning. The overall effective dose of fpVCT is comparable to that of MDCT scanning. Although current fpVCT technology has higher spatial resolution, its contrast resolution is slightly lower than that of MDCT (5-10HU vs. 1-3HU respectively). We discuss the efficacy and potential utility of fpVCT in various applications related to musculoskeletal radiology and review some novel applications for pediatric bones, soft tissues, tumor perfusion, and imaging of tissue-engineered bone growth. We further discuss high-resolution CT and omni-scanning (combines fluoroscopic and tomographic imaging).

Temporal Bone Imaging: Comparison of Flat Panel Volume CT and Multisection CT

American Journal of Neuroradiology, 2009

BACKGROUND AND PURPOSE: A recent development in radiology is the use of flat panel detectors in CT to obtain higher-resolution images. This technique is known as flat panel volume CT (fpVCT). We sought to compare the image quality and diagnostic value of 2 different flat panel detector-equipped scanners: one is a prototype fpVCT scanner, and the other is a so-called flat panel digital volume tomography (fpDVT) scanner, which is routinely used in clinical setup with current state-of-the-art multisection CT (MSCT) scanners. MATERIALS AND METHODS: Five explanted temporal bones and 2 whole-head cadaveric specimens were scanned with fpVCT, fpDVT, and MSCT scanners. The image series were blindly evaluated by 3 trained observers who rated 38 anatomic structures with regard to their delineation/appearance. RESULTS: Although the image quality obtained with fpVCT and fpDVT was rated significantly better compared with MSCT on isolated temporal bones, the differences were not significant when whole cadaveric heads were scanned. CONCLUSIONS: Theoretic and practical advantages exist for flat panel detector-equipped scanners, including improved image quality. However, when imaging whole cadaveric heads, no significant difference could be demonstrated between them and standard-of-care MSCT.

Three-dimensional imaging and cone beam volume CT in C-arm angiography with flat panel detector

Diagnostic and interventional radiology (Ankara, Turkey), 2005

We evaluated a new 3D angiography system with a flat panel detector (FPD) for its capabilitiy to acquire volume sets during a single rotation scan and to reconstruct high spatial resolution three-dimensional and cross sectional images, namely cone beam volume computed tomography (CBVCT) images. Present status of the technique, advantages and potential applications are discussed.

Introduction to the Language of Three-dimensional Imaging with Multidetector CT 1

The recent proliferation of multi– detector row computed tomography (CT) has led to an increase in the creation and interpretation of images in planes other than the traditional axial plane. Powerful three-dimensional (3D) applications improve the utility of detailed CT data but also create confusion among radiologists, technologists, and referring clinicians when trying to describe a particular method or type of image. Designing examination protocols that optimize data quality and radiation dose to the patient requires familiarity with the concepts of beam collimation and section collimation as they apply to multi– detector row CT. A basic understanding of the time-limited nature of projection data and the need for thin-section axial reconstruction for 3D applications is necessary to use the available data effectively in clinical practice. The axial reconstruction data can be used to create nonaxial two-dimensional images by means of multiplanar reformation. Multiplanar images can be thickened into slabs with projectional techniques such as average, maximum, and minimum intensity projection; ray sum; and volume rendering. By assigning a full spectrum of opacity values and applying color to the tissue classification system, volume rendering provides a robust and versatile data set for advanced imaging applications. Abbreviations: AIP average intensity projection, MinIP minimum intensity projection, MIP maximum intensity projection, MPR multi-planar reformation, SSD shaded surface display, 3D three-dimensional RadioGraphics 2005; 25:1409 –1428 ● Published online 10.1148/rg.255055044 ● Content Codes:

A prototype table-top inverse-geometry volumetric CT system

Medical Physics, 2006

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 ͑IGCT͒ 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 have the same axial, or slice direction, extent. This paper describes the implementation of the table-top IGCT scanner, which is based on the NexRay Scanning-Beam Digital X-ray system ͑NexRay, Inc., Los Gatos, CA͒ and an investigation of the system performance. The alignment and flat-field calibration procedures are described, along with a summary of the reconstruction algorithm. The resolution and noise performance of the prototype IGCT system are studied through experiments and further supported by analytical predictions and simulations. To study the presence of cone-beam artifacts, a "Defrise" phantom was scanned on both the prototype IGCT scanner and a micro CT system with a ±5°cone angle for a 4.5-cm volume thickness. Images of inner ear specimens are presented and compared to those from clinical CT systems. Results showed that the prototype IGCT system has a 0.25-mm isotropic resolution and that noise comparable to that from a clinical scanner with equivalent spatial resolution is achievable. The measured MTF and noise values agreed reasonably well with theoretical predictions and computer simulations. The IGCT system was able to faithfully reconstruct the laminated pattern of the Defrise phantom while the micro CT system suffered severe cone-beam artifacts for the same object. The inner ear acquisition verified that the IGCT system can image a complex anatomical object, and the resulting images exhibited more high-resolution details than the clinical CT acquisition. Overall, the successful implementation of the prototype system supports the IGCT concept for single-rotation volumetric scanning free from cone-beam artifacts.

C-arm flat detector computed tomography: the technique and its applications in interventional neuro-radiology

Neuroradiology, 2010

Introduction Flat detector computed tomography (FDCT) is an imaging tool that generates three-dimensional (3-D) volumes from data obtained during C-arm rotation using CT-like reconstruction algorithms. The technique is relatively new and, at current levels of performance, lags behind conventional CT in terms of image quality. However, the advantage of its availability in the interventional room has prompted neuro-radiologists to identify clinical settings where its role is uniquely beneficial. Methods We performed a search of the online literature databases to identify studies reporting experience with FDCT in interventional neuro-radiology. The studies were systematically reviewed and their findings grouped according to specific clinical situation addressed. Results FDCT images allow detection of procedural complications, evaluation of low-radiopacity stents and assessment of endosaccular coil packing in intra-cranial aneurysms. Additional roles are 3-D angiography that provides an accurate depiction of vessel morphology with low concentrations of radiographic contrast media and a potential for perfusion imaging due to its dynamic scanning capability. A single scan combining soft tissue and angiographic examina-tions reduces radiation dose and examination time. Ongoing developments in flat detector technology and reconstruction algorithms are expected to further enhance its performance and increase this range of applications.

Flat-panel CT versus 128-slice CT in temporal bone imaging: Assessment of image quality and radiation dose

European Journal of Radiology, 2018

We compared the image quality and radiation dose of flat-panel CT (FPCT) and multi-slice CT (MSCT) performed respectively with an angiographic unit and a 128-slice CT scanner. We investigated whether the higher spatial resolution of FPCT translated into higher image quality and we sought to eliminate inter-subject variability by scanning temporal bone specimens with both techniques. Materials and methods: Fifteen temporal bone specimens were imaged with FPCT and MSCT. Two neuroradiologists experienced in otoradiology evaluated 30 anatomical structures with a 0-2 score; 18 structures important from a clinical perspective were assigned a twofold value in calculation of the overall score. The radiation dose was calculated through the use of an anthropomorphic phantom. Results: The image quality was significantly higher for FPCT than MSCT for 10 of the 30 anatomical structures; the overall score was also significantly higher for FPCT (p = 0.001). The equivalent dose of the two techniques was very similar, but with different effective doses to the organs. Conclusion: FPCT performed on an angiographic unit provides higher image quality in temporal bone assessment compared to MSCT performed on a 128-slice CT scanner thanks to its higher spatial resolution, with comparable equivalent doses but different effective doses to the organs.