Surgery – Radioactive substance applied to body for therapy – Radioactive substance placed within body
Reexamination Certificate
2001-11-08
2004-08-03
Gilbert, Samuel G. (Department: 3736)
Surgery
Radioactive substance applied to body for therapy
Radioactive substance placed within body
C600S003000
Reexamination Certificate
active
06770021
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to a device and method for generating particles and electromagnetic radiation that may be used for treating a variety of disorders, such as cancer, tumors and the like and in particular, to a device and method for utilizing neutrons to kill or damage tumor cells within the body of a patient.
There are various diseases in which undesirable cells grow within the body of a patient. These diseases include various types of cancers and other diseases in which a large mass of undesirable cells are formed in the body of the patient. To effectively treat these types of diseases, it is desirable to surgically remove as many of the undesirable cells as possible and then attempt by other means to damage or kill the cells remaining after the surgery. The most insidious of these diseases is cancer in which cells multiply uncontrollably in the body causing pain and the eventual death of the patient.
There are some forms of cancer which are particularly deadly in that they spread very rapidly, are located in places that make it difficult to operate and remove them and/or are nearly always fatal to the patient. One of these particularly deadly forms of cancer is a brain tumor. A brain tumor, once diagnosed, may typically kill the patient within a very short time frame. The five-year survival rate after the diagnosis of glioblastoma multiforme (one of the most frequent malignant brain tumor type) is less than 1%. Therefore, it is desirable to be able to extend the life expectancy of a person with a brain tumor and to improve the quality of life of the patient during the remaining time in his/her life. Many different treatments for various cancers, including brain tumors, have been developed that attempt to reduce the size of the tumor or eliminate the tumor entirely.
The treatment of these cancers may be conducted using non-radiation types of treatments. For example, chemotherapy may be used in which toxic chemicals are targeted at the cancer or tumor cells (using various well known techniques to target the tumor or cancer cells) so that the cancer or tumor cells are damaged or killed by the toxic chemicals. The problem with chemotherapy is that the toxic chemicals also tend to damage other cells or organ systems in the body, and have undesirable side effects, such as nausea, vomiting etc., which lead to a poor quality of life of the patient. For a brain tumor, the treatment typically involves surgery to debulk the tumor (remove as much of the tumor as possible without causing further damage to the healthy cells) followed by some other treatment to combat the cells remaining in the brain after the surgery. The treatment after the surgery may include various types of radiation treatment, as described below, which attempt to kill or damage the remaining cancer or tumor cells. The problem with this surgery and radiation treatment approach is that some brain tumors are inoperable and the radiation treatment alone does not sufficiently combat the tumor. Due to these limitations, other radiation or particle emitting treatments have been developed.
In the past, various types of radiation and particle emitting devices have been used for treating various diseases and maladies. The purpose of these devices is to destroy or disable the undesirable cells, such as tumor cells or cancer cells. To destroy or damage the undesirable cells, the particles or electromagnetic energy may strike and break the chemical bonds within the cancer cells so that these cells are destroyed. In any case, the radiation or particle energy must be highly focused on the tumor or cancer cells because the healthy cells surrounding the tumor or cancer cells are equally susceptible to radiation or particle damage. The goal, therefore, is to damage the cancer to tumor cells sufficiently with the radiation or particle energy to cause cell death while limiting the exposure of the healthy cells to the damaging particles and radiation. In particular, typical cells can repair some particle or radiation damage. Thus, the healthy cells with a more limited exposure than the tumor can repair the damage while the tumor or cancer cells cease functioning or die since they have been exposed to a larger dose of radiation or particles.
One typical technique for treating cancer or tumor cells is radiation treatment in which electromagnetic radiation is directed towards the tumor or cancer cells in order to damage the tumor or cancer cells. The radiation may be x-rays or other types of electromagnetic energy. The radiation is typically generated by a source outside the body, passes through the skin and tissue surrounding the tumor or cancer cells and is focused on the tumor or cancer cells so that a majority of the radiation energy is focused on the tumor or cancer cells. The problem with radiation treatment is that, to treat tumor or cancer cells inside of the body, the radiation must pass through surrounding healthy tissue which needs to be protected as much as possible from the radiation damage. Therefore, the amount of radiation energy that can be directed at the tumor cells during each treatment is limited by the amount of radiation that the surrounding healthy cells may be exposed to during each treatment. For example, if the dose to the surrounding healthy cells is too high, the healthy cells will also die which is undesirable. In addition, after a radiation treatment, the healthy surrounding cells must be given a chance to repair the damage before any further radiation treatment occurs. Therefore, due to the limited amount of radiation that may be directed to the tumor or cancer cells during each treatment and the period of time between each treatment to permit the healthy cells to repair, radiation treatments are delivered over many weeks. Thus, radiation treatment requires quite some time to damage the tumor or cancer cells sufficiently to kill them and may still cause a fair amount of damage to the surrounding healthy cells since the radiation must pass through the surrounding healthy cells.
Another typical technique for treating tumor or cancer cells is to use brachytherapy treatment in which a radiation source is inserted into or near the tumor so that the radiation from the radiation source is more focused into the tumor cells with less damage to the surrounding healthy cells. The radiation sources may include various elements that emit various types of radiation or particles including beta particles and gamma photons. Gamma photons and beta particles are referred to as low linear-energy-transfer (LET) radiation particles in which a particle transfers a small amount of its energy to a tumor cell on each passage. To be effective on cell killing, the small amount of energy transferred to each cell must be converted to free radicals via interacting with the oxygen existing in the cell. Therefore, a low LET radiation treatment is naturally ineffective to cancer cells that are hypoxic (have less oxygen than typical healthy cells). One type of hypoxic tumor cells are found in brain tumors.
Instead of these low LET radiation, it is also possible to use high LET radiation sources, such as neutrons. See R. A. Patchell et al., “A phase I trial of neutron brachytherapy for the treatment of malignant gliomas”,
The British Journal of Radiology,
Vol. 70, pp. 1162-1168 (November 1997). These neutron sources emit neutrons (a helium nucleus) which interact with the tumor cells to kill or damage them. A high LET radiation particle typically deposits a large fraction of its energy to a cell on each passage, and its cell killing effect is not affected by the amount of oxygen that is in the cells. Therefore, a neutron treatment is equally effective in killing or damaging both normal tumor cells and hypoxic tumor cells. The neutron source may be a radioactive element, such as californium (Cf), that may be internally placed near the tumor cells (i.e. the brachytherapy source) or an external neutron beam produced by a nuclear reactor or proton/deuteron accelerator. In a neutron therapy, neutrons typ
Gilbert Samuel G.
Gray Cary Ware & Freidenrich LLP
Isotron ,Inc.
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