Validation Framework and Software Toolkit

Validation Framework

validation1Various needle tracking technologies have been developed using ultrasound, electromagnetic sensors, and optical sensors. To evaluate these new needle tracking technologies, 3D volume information is often acquired to compute the actual distance from the needle tip to the target object. The image-guidance conditions for comparison are often inconsistent due to the ultrasound beam-thickness. Since 3D volumes are necessary, there is often some time delay between the surgical procedure and the evaluation. These evaluation methods will generally only measure the final needle location because they interrupt the surgical procedure. We design a new platform for evaluating needle tracking systems in real-time, resolving the problems stated above. We developed new tools to evaluate the precise distance between the needle tip and the target object. A PZT element transmitting unit is designed as needle introducer shape so that it can be inserted in the needle. We have collected time of flight and amplitude information in real-time.

One of the advantages of using the proposed system is that we can minimize unfair conditions caused by ultrasound beam-thicknes before beginning a procedure. Since the fiducial can also transmit ultrasound, we can place it at the mid-plane of an ultrasound probe with sub-millimeter accuracy. With this validation system, we accomplished immediate measurements, and minimized the beam-thickness problem. It also provides information of the distance and amplitude profile over an entire operation.

 

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Figure. An example of ultrasound-guided system, comparison between conventional evaluation methods and ultrasound tool tracking evaluation platform; (a) Real-time evaluation. (b) Ultrasound Beam-thickness. (c) Time-series distance information.

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Block diagram of two designed systems.

Software Toolkit

toolkit1Acquisition of ultrasound (US) pre-beamformed radio-frequency (RF) data is essential in photoacoustic (PA) imaging research. Moreover, 3D PA imaging can provide volumetric information for a target of interest. However, existing 3D PA systems require specifically designed motion stages, an ultrasound scanner and a data acquisition system to collect 3D pre-beamformed RF data. These systems are incompatible with clinical ultrasound systems and are difficult to reconfigure and generalize to other PA research. To overcome these limitations, we proposed and developed a new software framework for spatially-tracked pre-beamformed RF data acquisition with a conventional 2D ultrasound transducer and external tracking device. We upgraded our previous software framework using task-classes of OpenIGTLinkMUSiiC2.0 and MUSiiCToolkit 2.0. We also improved our MUSiiCToolKit 2.0 by adding MUSiiCNotes 2.0, a collection of specific task-classes for US research. MUSiiC-DAQServer2.0, MUSiiC-TrackerServer and MUSiiCSync are the main modules of our software framework. Spatially-tracked 2D PA frames are collected efficiently using this software framework for 3D PA research and imaging. The software modules of our software framework are based on the concept of network distributed modules and can simultaneously support multiple-client connections via TCP/IP network. In addition, the collected 2D PA frames are compatible with other MUSiiCToolKit 2.0 modules such as

MUSiiC-Beamform, MUSiiC -BMode and MUSiiC – ImageViewer modules. These aspects of our software framework allow us to easily reconfigure and customize our system to other PA or US research.

Our software framework using an external tracking device allows for arbitrary and unrestricted US probe motion and provides spatial-tracking information with three translational and three rotational degrees of freedom. Spatially-tracked 2D PA frames with a conventional handheld 2D US probe were collected efficiently with our framework. Moreover, 3D PA volumes can be reconstructed from the collected 2D PA frames using their spatial tracking information, without the need for expensive motion stages or custom US scanners.

 

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Block diagram of (a) MUSiiC-DAQServer2.0 module and (b) MUSiiC-TrackerServer module

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Block diagram of MUSiiC-Sync module