Techniques for enhancing real-time CORBA quality of service

Pyarali, Irfan; Schmidt, Douglas C.; Cytron, Ron K.

doi:10.1109/jproc.2003.814616

Cited by 37 publications

(19 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…k-Space data was transferred directly from the MR acquisition system to an external in-house-developed realtime reconstructor using The Ace Orb (TAO) a real-time implementation of the Common Object Request Broker Architecture (CORBA) communication protocol (17). The entire reconstruction was implemented as a multithreaded processing chain in Cϩϩ/OpenMP on a four-processor AMD Opteron (2.4 GHz).…”

Section: Real-time In-vivo Studymentioning

confidence: 99%

Real‐time geometric distortion correction for interventional imaging with echo‐planar imaging (EPI)

Dragonu¹,

Senneville²,

Quesson³

et al. 2009

Magnetic Resonance in Med

View full text Add to dashboard Cite

In typical interventional procedures such as catheter tracking, MR-guided biopsies, or MR-guided thermal ablation, rapid MR-imaging is typically used to provide functional or positional information in real-time, which is used to retroactively control the interventional procedure. In general, this requires rapid MR-sequences coupled with fast data processing strategies to achieve high frame-rates and low image latencies, allowing guidance of the interventional process and resolution of physiological motion.Although a large variety of sequences, such as multiecho balanced steady-state free precession (e.g., TrueFISP) (1) or single-shot echo-planar-imaging (EPI) (2), have been used for this purpose, many rely on EPI readout trains for rapid data acquisition (3,4). However, EPI images suffer from geometric distortions due to off-resonance effects resulting from static magnetic field (B 0 ) inhomogeneities, from susceptibility changes between different anatomical regions especially near tissue/air and tissue/bone interfaces and from eddy-current effects. These distortions may lead to positional errors if the images are used for guiding external interventional devices.Several correction techniques for geometric distortions have been proposed in the past, such as field inhomogeneity mapping (5,6), point-spread function calculation (7), or dynamically switched phase ramp in kt-space (8). The main limitations of these methods arise either from the inability to rapidly update the distortion information during the acquisition or from the introduced additional computational overhead, which may render them unsuitable for real-time image processing. Another interesting B 0 mapping-based approach was recently proposed by Priest et al. (9) using two reduced acquisitions interleaved (TRAIL). This method collects correction data by acquiring dual-echo images with halved image resolution. However, this method requires for the reconstruction the combination of nonsequentially-acquired half-resolution images, which can be a limiting factor in resolving rapid motion. Furthermore, TRAIL suffers from an intrinsic signal loss of ͱ2, which is particularly limiting for interventional applications in regions with short T* 2 such as abdomen or thorax.We propose a distortion-correction based on field maps, as suggested by Reber et al. (6) in combination with a dynamic update strategy for the correction data and timeefficient data processing, as a simple and efficient method for the real-time correction of geometric distortions in gradient-recalled EPI images. The field maps are temporally updated to compensate for dynamic changes induced by physiological motion or the displacement of interventional devices, by continuously acquiring EPI images with alternating echo-time (TE) values. The proposed approach does not require additional acquisitions, and all the acquired images are used to correct for geometric distortions on the fly.The proposed method may be particularly useful for MR-guided thermal therapies that induce local hyperthermia usi...

show abstract

Section: Real-time In-vivo Studymentioning

confidence: 99%

Real‐time geometric distortion correction for interventional imaging with echo‐planar imaging (EPI)

Dragonu¹,

Senneville²,

Quesson³

et al. 2009

Magnetic Resonance in Med

View full text Add to dashboard Cite

show abstract

“…RTZen also includes many of the performance and predictability enhancing techniques pioneered in ZEN [18][19][20] and TAO [21][22][23][24]. For example, RTZen's thread pool implements the Half-Sync/Half-Async pattern [9] to minimize complexity and allow high throughput, and the POA uses active-demux tables to allow O(1) demultiplexing of server-side objects.…”

Section: Scoped Memorymentioning

confidence: 99%

“…The research community has determined the strengths and limitations of CORBA as foundation for DRE systems [39,40], and based on them, researchers have proposed i) software architecture designs [25,23], ii) scheduling approaches and mechanisms [41][42][43], iii) techniques for improving quality of service [44,24], iv) extensions for real-time network protocols [25,[45][46][47], v) the adaptation of CORBA services [48,49], vi) techniques for tailoring CORBA ORBs to computational platforms under stringent resource constraints [50,51,13], and vii) modeling and verification methods [52]. Meanwhile, the Object Management Group has produced the Real-Time CORBA specifications [53,17].…”

Section: Related Workmentioning

confidence: 99%

RTZen: Highly Predictable, Real-Time Java Middleware for Distributed and Embedded Systems

et al. 2005

View full text Add to dashboard Cite

Abstract. Distributed real-time and embedded (DRE) applications possess stringent quality of service (QoS) requirements, such as predictability, latency, and throughput constraints. Real-Time CORBA, an open middleware standard, allows DRE applications to allocate, schedule, and control resources to ensure predictable end-to-end QoS. The Real-Time Specification for Java (RTSJ) has been developed to provide extensions to Java so that it can be used for real-time systems, in order to bring Java's advantages, such as portability and ease of use, to real-time applications. In this paper, we describe RTZen, an implementation of a Real-Time CORBA Object Request Broker (ORB), designed to comply with the restrictions imposed by RTSJ. RTZen is designed to eliminate the unpredictability caused by garbage collection and improper support for thread scheduling through the use of appropriate data structures, threading models, and memory scopes. RTZen's architecture is also designed to hide the complexities of RTSJ related to distributed programming from the application developer. Empirical results show that RTZen is highly predictable and has acceptable performance. RTZen therefore demonstrates that Real-Time CORBA middleware implemented in real-time Java can meet stringent QoS requirements of DRE applications, while supporting safer, easier, cheaper, and faster development in real-time Java.

show abstract

“…Before DT1 migrates back to Host 1, DT2 migrates from Host 2 to Host 1. For efficiency, flexible concurrency strategies, such as thread pools [15], may map distributable threads to whatever local threads are available. For example, Figure 5 shows DT2 mapped to OS thread 1 and when DT1 migrates back to Host 1 it is mapped to OS thread 2.…”

Section: Rtc12 Implementation Challengesmentioning

confidence: 99%

Enhancing adaptivity via standard dynamic scheduling middleware

et al. 2004

View full text Add to dashboard Cite

show abstract

Techniques for enhancing real-time CORBA quality of service

Abstract: End-to-end TAO, which is widely-used, open-source, Real-time CORBA-compliant DRE middleware.

Cited by 37 publications

References 28 publications

Real‐time geometric distortion correction for interventional imaging with echo‐planar imaging (EPI)

Real‐time geometric distortion correction for interventional imaging with echo‐planar imaging (EPI)

RTZen: Highly Predictable, Real-Time Java Middleware for Distributed and Embedded Systems

Enhancing adaptivity via standard dynamic scheduling middleware

Contact Info

Product

Resources

About