USER-DEFINED SIZE AND CONTRAST THREE DIMENSION (3D)-PRINTED FEATURES FOR RADIONUCLIDE PHANTOMS
Publication Date: 2017-Apr-06
The IP.com Prior Art Database
A technique to enable a user defined size and contrast three dimension (3D) printed features for radionuclide phantoms is disclosed. The technique enables use of larger contrast objects at lower contrast than the 3:1 defined using hollow three dimensional (3D) printed objects is disclosed. The technique also enables imaging of many such objects within a single phantom, where both feature size (outer extent) and contrast are controlled. Consequently, the technique enables comparison between scanners with the same phantom. The technique includes a design using multiple concentric spherical springs printed in a non porous material with controlled construction parameters. This allows creation of fixed size features but at user specified contrasts when embedded in a background of random close packed beads. The upper limit of contrast is open inside while the lower limit is with the feature open space equal to the open space between the background beads. For instance, the ratio of space occupied by material to the open space is 3:1.
The present invention relates generally to an imaging phantom, and more particularly to a technique for enabling user defined size and contrast three dimension (3D) printed features for radionuclide phantoms.
Generally, imaging phantom is an object that is scanned or imaged to evaluate, analyze, and tune performance of several imaging devices. The imaging phantom evaluates the way imaging device is likely to respond in a similar manner to the way human tissues and organs are likely to behave in that specific imaging modality. For instance, phantoms made for two-dimensional (2D) radiography may hold various quantities of X-ray contrast agents with similar X-ray absorbing properties to normal tissue to tune a contrast of the imaging device or modulate exposure of patients to radiation.
A state of the art technique describes methods for 3D printing regular dodecahedral exoskeletons and standard spherical springs to serve as contrast features in a radionuclide phantom. Figure 1 depicts an example CAD model of a spherical spring. Figure 1a depicts cross section of a typical 6mm version with a 1 mm diameter side element. Figure 1b depicts 6 mm inscribed sphere without and with a bar. Figure 1c depicts a 4 mm version. Figure 1d depicts a 12 sided dodecahedron with two nearby solid beads.
One of the methods includes placing hollow 3D printed objects into a tank filled with small, non-porous beads that are of diameter large enough to avoid entering the dodecahedral or spherical spring structure. When a pre-mixed radionuclide solution is poured into such a configuration, the 3D printed objects fill inside at the full concentration while the outside background beads only fill between beads. The apparent background radionuclide concentration is reduced to a scanning system, wherein the reduction is defined by a bead packing fraction. For regular packing, the reduction is about 4:1, while for random close packing, the reduction is approximately 3:1. The latter case is encountered in phantoms that are tested to date. The voids created by the 3D printed objects make contrast features of a user definable size and many can be located within a phantom without supporting structures. Consequently, 3D images of the features are achievable. Feature contrast can be reduced by including material inside the features during the 3D printing process. However, this is an ideal imaging situation when lesion detectability phantoms are designed since detectability of a size feature is not known theoretically.
Therefore, it would be desirable to have a technique to provide fine tuning of the imaging situation.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 depicts an example CAD model of a spherical spring. Figure 1a depicts cross section of a typical 6mm version with a 1 mm diameter side element. Figure 1b depicts 6 mm inscribed sphere without and with a bar. Figure 1c...