Patent Application
20080023636
The invention is pointed out with particularity in the claims. The above and further advantages of this invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:
a is a graph depicting photon stopping power of a tungsten collimator in accordance with an embodiment of the present invention;
b is a graph depicting photon stopping power of a lead collimator in accordance with the prior art; and
c is a graph depicting photon stopping power of a tungsten polymer collimator in accordance with an embodiment of the present invention.
A tungsten polymer collimator according to an exemplary embodiment of the instant invention is intended to substantially accomplish the foregoing objectives.
Examples of the more important features of this invention have thus been summarized rather broadly in order that the detailed description thereof that follows may be better understood and in order that the contribution to the art may be better understood. There are, of course, additional features of the invention that will be described hereinafter and which will also form the subject of the claims.
Referring now to the figures,
For example, in accordance with the invention as shown in
In a further preferred embodiment, a tungsten polymer collimator can be formed to have a thickness T of from 0.01 to 1.1 cm. In other embodiments, the tungsten collimator thickness T is from 0.1 to 1.0 cm. In still another embodiment, the tungsten collimator has a thickness T of from 0.2 to 0.9 cm. In yet still another embodiment, the tungsten collimator T has a thickness of from 0.3 to 0.8 cm. In a further embodiment, the tungsten collimator has a thickness T of from 0.4 to 0.7 cm. In a yet further embodiment, the tungsten collimator has a thickness T of from 0.5 to 0.6 cm.
A method for fabricating a tungsten polymer collimator can comprise mixing tungsten powder, small particles and/or filings, etc. with a polymer binder using known methods for fabricating polymers to form a tungsten polymer wherein the tungsten is essentially locked within the polymer. In some embodiments, the tungsten and polymer can be mixed to homogenously distribute the tungsten throughout the polymer binder. Thereafter, the tungsten polymer can be submitted to a polymer fabrication process so as to form a collimator. Examples of fabrication methods include, but are not limited to: molding, extruding, machining, forming, rolling and bonding.
Preferably, the tungsten polymer collimator has a density that substantially equivalent to lead and is between 8 and 12 g/cc. In other embodiments, the tungsten polymer collimator has a density between 9 and 11 g/cc. In yet other embodiments, the tungsten polymer has a density of 10 g/cc.
It will be recognized by those skilled in the art from this disclosure that a tungsten polymer collimator according to the invention can be fabricated to any of a slat, parallel hole, pinhole, multi-pinhole, square hole, hexagonal hole, fan beam, diverging and converging beam collimator, or combinations thereof. Furthermore, as previously indicated, the use of tungsten polymer allows the collimators to more readily undergo post fabrication procedures that may be required to form complex structures. For example, because it is not as malleable as lead and is non-toxic, tungsten polymer collimators can be subjected to procedures such as milling, drilling, sanding, etc., which may not be available for lead collimators.
In a preferred embodiment, a tungsten polymer collimator according to the invention is configured for use with a nuclear imaging device, such as a PET or SPECT imaging device, and is capable of preventing amounts radiative particles from colliding with a detector assembly thereof. In one embodiment, a tungsten polymer collimator for a nuclear imaging device has at least 50% by weight of tungsten. In such embodiment, the tungsten polymer is formed by mixing powdered tungsten with a polymer such that the tungsten polymer has a density between 9-12 g/cc. In some embodiments the tungsten collimator can be configured to comprise a photon stopping power of 0.05 to 50%. In some embodiments, when the thickness of the collimator is between 0.01 to 1.0 cm and photons having energy levels from 50 to 200 keV are directed toward the collimator, the tungsten polymer collimator has a stopping power of from 0.5 to 50%. In other embodiments the tungsten collimator can be configured to have a photon stopping power of from 10 to 40%. In some embodiments, the tungsten collimator can have a photon stopping power of from 20 to 30%. In still other embodiments, a tungsten polymer collimator can be configured for stopping photons having energy levels from 50 to 200 keV. In other embodiments, the tungsten polymer collimator can be configured for stopping photons having energy levels from 100 to 150 keV.
Referring now to
It is understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is define by the scope of the appended claims. Other aspects, advantages and modifications are within the scope of the following claims.
