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Publication Date: 2016-May-17
Document File: 4 page(s) / 402K

Publishing Venue

The Prior Art Database


A technique of modifying conventional phantom design so as to include more and smaller spheres in the phantom is disclosed. The modified phantom design includes spheres at same sizes and locations as those in conventional phantom design. The technique includes three dimensional (3D) printing of phantoms and components of phantoms. Multiple expandable bladders are connected with small‐bore, semi-rigid tubes. The multiple expandable bladders are placed empty within rigid 3D printed regular dodecahedrons of a specified size within a phantom. The bladders are filled via a single connector to outside of phantom tank and with a syringe of pre‐defined volume.

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The present invention relates generally to image quality phantoms and more particularly to a technique for controlling size and placement of a filled object in a phantom.

Generally, evaluation of performance characteristics of an imaging device, such as, positron emission tomography (PET) is conducted using a National Electrical Manufacturers Association (NEMA) image quality phantom. The NEMA image quality phantom is originally derived from the International Electrotechnical Commission (IEC) phantom of similar construct. The phantom utilizes six fillable spheres of variable sizes. The spheres are mounted using acrylic tubes and each fills separately. The four smallest spheres are filled at a target of 4:1 contrast to background while the two largest spheres are filled with non‐radioactive water.

A conventional phantom design includes multiple numbers of smaller spheres to characterize higher resolution imaging systems. Figure 1 depicts the conventional phantom design with multiple numbers of smaller spheres.

Figure 1

Figure 2 represents (a) top view and (b) side view of the conventional phantom design.


(a)                                       (b)

Figure 2

As the sphere size becomes smaller, effects due to partial volume become proportionally larger. Similarly, imaging result depends upon placement of sphere in the phantom. Multiple numbers of smaller spheres are included to allow sampling positioning effects during a single measurement.  Extending the phantom to include more spheres, however, is problematic. The problem arises due to difficulty in filling multiple numbers of spheres without any air trapping. As spheres become smaller, air trapping becomes more problematic. Further, impact of cold sphere walls becomes larger with reduction in sphere size. As repeatability of phantom measurements relies on capability of a user to fill the phantom in a repeatable manner, adding more spheres within the conventional phantom design reduces a likelihood of reproducible results.  

In order to fill multiple spheres with efficiency, a conventional technique is known in the art that employs an apparatus with a housing having an opening at a first end and a plurality of holes at a second end. A plurality of hollow tubes is attached to the plurality of holes, a plurality of containers removably attached to the hollow tubes, and a plurality of elastic fasteners. Each elastic fastener is clamped to each container to a corresponding hollow tube, such that, when the containers are filled with fluid and detached from the corresponding hollow tubes, each elastic fastener seals each container with a fluid inside. Figure 3 depicts single fill bunch of balloons as described in the above mentioned conventional technique.

Figure 3

However, the conventional technique does not find application for filling spheres in imaging phantoms.

Therefore, it would be desi...