Coating apparatus – Control means responsive to a randomly occurring sensed... – Responsive to condition of coating material
Reexamination Certificate
2000-07-05
2002-10-08
Crispino, Richard (Department: 1734)
Coating apparatus
Control means responsive to a randomly occurring sensed...
Responsive to condition of coating material
C118S323000
Reexamination Certificate
active
06461433
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus and a method for precisely applying radioactive material onto a substrate, e.g. a brachytherapy device or the like. More particularly, the present invention relates to materials and processes for fabricating brachytherapy devices with precisely controlled amounts of radioactive or precursor materials in precisely controlled positions within such devices. The present invention marries two heretofore-disparate technologies, namely those of inkjet printing and of the fabrication of devices for brachytherapy.
2. Description of Related Art
Inkjet printing is used to print a precise amount of ink on a substrate in a precisely defined pattern. Inkjet printheads operate by one of two methods: the so-called, “continuous inkjet” process (“CIJ”), and the “drop-on-demand” process (“DOD”). In DOD inkjet printing, there are two commonly used technologies by which ink droplet ejection is achieved. These technologies are thermal (or bubble-jet) inkjet printing and piezo-electric (or impulse) inkjet printing. In thermal inkjet printing, the energy for ink drop ejection is generated by resistor elements which are electrically heated. Such elements heat rapidly in response to electrical signals controlled by a microprocessor and create a vapor bubble which expels ink through one or more jets associated with the resistor elements. In piezo-electric inkjet printing, ink drops are ejected in response to the vibrations of a piezo-electric crystal. The piezo-electric crystal responds to an electrical signal controlled by a microprocessor.
The localized treatment of tumors and other medical conditions by the interstitial implantation of radioactive materials is a recognized treatment modality of long standing. Radioactive implants are used to provide radiation therapy in order to destroy tumors or reduce or prevent the growth of tumors. Radioactive implants are also used to prevent the growth of microscopic metastatic deposits in lymph nodes that drain the region where a tumor has been removed. Implants are also used to irradiate the postoperative tumor bed after the tumor is excised. Implantation of radioactive sources directly into solid tumors for the destruction of the tumors is used in a therapy referred to as brachytherapy.
For example, U.S. Pat. No. 3,351,049 to Lawrence discloses the use of low-energy X-ray-emitting interstitial implants as brachytherapy sources. Such implants, especially those containing palladium (Pd-103) or iodine (I-125) as the radioactive therapeutic isotope, have proven to be highly effective against solid malignancies. Excellent results have been obtained when such devices have been used against early-stage prostate cancer. These devices, or “seeds,” must be very small because they are typically placed in the diseased organ through a hollow needle. Once implanted in the organ, they are held in place by the surrounding tissue or stitched in place with an associated suture. A typical size for a permanent implant is a rod or cylinder 0.8 mm in diameter by 4.5 mm long. A temporary implant is typically inserted into the tissue to be treated through a hollow needle or a plastic sleeve and has approximately the same outside diameter as a permanent implant of about 0.8 mm.
An essential step in the fabrication of these tiny brachytherapy devices is the inclusion in each device of a small amount of a radioactive isotope. U.S. Pat. No. 4,323,055 to Kubiatowicz, U.S. Pat. No. 4,702,228 to Russell, U.S. Pat. No. 5,405,309 to Carden and U.S. Pat. No. 5,713,828 to Coniglione disclose technologies addressing the fabrication of brachytherapy devices. Technology disclosed in the aforementioned patents has been used to develop the processes presently used in the production of commercially available Pd-103 and I-125 seeds. The revenue from the sale of such seeds in the United States in 1997 is estimated to have been about sixty million dollars.
Notwithstanding the commercial success of present methods of brachytherapy device fabrication, the present technology does not provide ways of making brachytherapy devices that contain precisely controlled amounts of radioactive material so as to provide devices for specific orders or to provide treatment tailored to therapy requirements. Nor does it provide ways of making brachytherapy devices that contain precisely positioned amounts of radioactive material so at to provide devices with radiation fields of a controlled shape to meet therapy requirements. Nor does it provide ways of making individually produced brachytherapy devices so as to control wastage of radioactive material and meet the needs of individual customers. Nor does it provide ways of automating production of brachytherapy devices to reduce radiation exposure during manufacture, to reduce the fabrication time and to improve the uniformity of the finished product.
SUMMARY OF THE INVENTION
The inventions disclosed herein include a novel method for fabricating radiation-emitting elements, such as brachytherapy devices, and a brachytherapy device made by the novel method. The method and device disclosed herein provide improvements that can meet the various needs enumerated above.
The present invention provides a novel method for producing a radiation-emitting element consisting of a substrate onto which a radioactive fluid has been deposited in a predetermined pattern and quantity. The fluid is generally solidified (i.e. “cured”) such as by polymerization or drying, before the radiation-emitting element is used.
An embodiment of the present invention comprises depositing a predetermined amount and pattern of a radioactive fluid onto a surface of a substrate as drops from a fluid-jet printhead. The technology associated with inkjet printing is generally applicable to the deposition of any fluid, whether or not such a fluid has the properties of an ink. Accordingly the term “fluid-jet” rather than “inkjet” is used herein, though the reader should understand that apparatus and methods used heretofore for inkjet printing may generally be adapted for use with the present invention, as more fully described below. Inkjet printheads reproducibly apply droplets of precise volumes to precise positions on substrates.
In particular embodiments of the present invention, individual drops of a radioactive material are deposited by a fluid-jet printhead in a predetermined pattern. Such a pattern may comprise a plurality of bands, dots or areas.
In a further embodiment of the present invention, a series of radiation-emitting elements are produced in succession, using feedback to fine tune the production of a subsequent deposited substrate based on a measurement from a previous one. The amount of radioactive fluid to be deposited on the present substrate is determined by measuring the amount or pattern of radioactive fluid deposited on a preceding substrate and accordingly adjusting the amount or pattern of radioactive fluid to be applied to the present substrate.
In a further embodiment of the present invention, the substrate has a surface over which a partially radiation-attenuating element is to be secured. This may be the cylindrical outer casing of a hollow seed brachytherapy device such as disclosed in the '828 patent. To compensate for the attenuation of radiation by such an element, one measures the radiation-attenuating properties of the partially radiation-attenuating element; and then computes from that measurement the amount and position of the radioactive fluid to be deposited from the printhead onto the substrate so as to compensate for the measured radiation attenuating properties and thereby produce a desired radiation field external to the casing, or partially radiation-attenuating element. The radioactive fluid from the fluid-jet printhead is then deposited in predetermined amounts at predetermined locations on the surface of the substrate as so computed, and the partially radiation-attenuating element is secured in position. For further precision, the radiation-attenuating characteristic
Carden, Jr. John L.
Fox James Edward
Hudd Alan Lionel
Russell, Jr. John L.
Willis Michael
Crispino Richard
Elman Gerry J.
Elman & Associates
International Brachytherapy S.A.
T. Yewebdar T.
LandOfFree
Fluid-jet deposition of radioactive material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fluid-jet deposition of radioactive material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluid-jet deposition of radioactive material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2986100