Surgery – Radioactive substance applied to body for therapy – Radioactive substance placed within body
Reexamination Certificate
2001-11-21
2003-09-30
Winakur, Eric F. (Department: 3736)
Surgery
Radioactive substance applied to body for therapy
Radioactive substance placed within body
C604S019000
Reexamination Certificate
active
06626817
ABSTRACT:
RELATED APPLICATIONS
The present application claims the benefit of priority to Applicant's co-pending German Patent Application No. 10058163.3, filed in Germany on Nov. 22, 2000.
1. Field of the Invention
The present invention relates to a method and an apparatus for positioning radiation sources by way of hollow needles for the purpose of achieving an optimal dosage distribution during the introduction of various radiation sources in biological tissue. The method and the apparatus are particularly well suited for the treatment of prostate cancer with weak radioactive radiation sources (e.g., seeds).
2. Background of the Invention
In brachytherapy, tumour tissue is subjected to radiation from the shortest possible distance. This is accomplished, for example, with small radioactive and/or gamma-radiating sources which are inserted by way of hollow needles into the tumour tissue. Conventionally, a tumour is punctured by several hollow needles. In this particular case, two different methods of treating tumour tissue are typically employed.
According to a first method, a radiation source having a strong dosage of radiation is exposed to the tumour tissue. The radiation sources are put into the needles for a short period and are then taken out again. The radiation is discharged through the wall of the hollow needles. The treatment is repeated as required. The radiation sources have a very large half-life period in the magnitude of years.
According to a second method, a radiation source having a low dosage of radiation is exposed to the tumour tissue. The seeds are grain size and are discharged or implanted through the hollow needles into the tissue. The seeds remain in the tissue. The half-life period of these radiation sources amount to weeks and/or months and, during this period, the radiation drops below a therapeutic or harmful effect. For the treatment of the tumour tissue, for example, weak radioactive isotopes of the elements iodine, cobalt or palladium are typically applied.
In this second case, it is important, in order to achieve the greatest therapeutic benefit, that the dosage distribution be as uniform as possible and be located in the tumour tissue (e.g., prostate tissue) at a high level.
It is also important that the healthy tissue (e.g., the urethra tissue, the seminal vesicle tissue, etc.) shall not be subjected to radiation above a maximum dosage, which may cause renewed or protracted diseases of the healthy tissues.
In conventional systems, an amount of similar seeds having the same radiation dosage and half-life period are typically placed in the tumour tissue. In order tomaximize the therapeutic benefits, a software for dosage planning may be employed. The software determines the positions of the seeds in a Cartesian coordinate system relative to an extra-corporally secured perforated raster plate. In a conventional system, the perforated raster has a 5 mm clearance between the holes. The needles for the seed implantation are guided through the perforated raster in accordance with the specified details of the dosage planning software. They are inserted through the skin and healthy tissue and into the tumour tissue. For depth checking purposes, either a scale applied to the needles is adopted or a mechanical scale in addition to the needle is employed.
Conventionally, there are two basic methods for inserting the seeds. According to a first method, the insertion is performed by inserting hollow needles which are loaded up to the needle tip with a seed strand (e.g., RAPID STRAND™) made up of similarly therapeutic seeds. The seed strand is then anchored at the needle tip in the tissue and the needle is withdrawn. In this case, the seed strand remains in the tissue.
Two methods for the manufacture and the use of seed strands are typically employed. U.S. Pat. No. 5,460,592 to Langton et al. discloses a device for the manufacture and transport of seeds that are embedded in a bio-absorbable material. After an intervention planning, the strands are taken from a transport vessel and shortened to the required length before they are located in hollow needles. U.S. Pat. No. 5,938,583 to Grimm discloses a hollow needle that is particularly easy to fill and withdraw. U.S. Pat. No. 6,010,446 discloses a bio-absorbable spacer seed between the seeds that allows a time-related manufacture of seed strands.
A product description for “RADIOACTIVE SEED SHUTTLE” of Messrs MED-TEC (P.O. Box 320, Orange City, Iowa 51041, U.S.A.) discloses a corresponding product whose mode of function, however, is not described. Furthermore, a product description for “EXPRESS SEEDING CARTRIDGE” from the year 1999 of Messrs Indigo Medical Inc. (10123 Alliance Road, Cincinnati, Ohio, 45242) discloses a pre-loaded seed cartridge for the direct filling of a needle.
Referring back to the various methods of inserting seeds, the second conventionally employed method of inserting seeds involves the insertion of hollow needles through which individual seeds (e.g., free seeds) are later discharged at the needle tip. In this case, the individual seeds are discharged individually and manually by way of an apparatus at the needle tip. After this, the needle is withdrawn via a mechanical raster, manually in accordance with the planned seed clearance in the planning raster before the next individual seed is discharged. The individual seeds are re-loaded by way of a spring-based magazine. Such an apparatus is disclosed in U.S. Pat. No. 5,860,909.
In addition, U.S. Pat. No. 6,102,844 discloses a solution whereby the manual discharge of the seeds is fibre-optically monitored. In this case, and contrary to the method disclosed in U.S. Pat. No. 5,860,909, a revolver magazine is used which is very mechanically sophisticated. In addition, WO 00/61229 A1 discloses the taking of different seeds and/or seeds mixtures for the treatment. The position of the needle relative to a position reference block is visually illustrated in this case, as is the detection of an optimal seed deposit position. The selection of a magazine and a seed to be discharged from the revolver magazine is determined from the current position of the needle in the tissue. Furthermore, U.S. Pat. No. 5,906,574 discloses how the establishment of the connection to the treatment plan for an optimal treatment can be derived.
Conventionally, the seeds are supplied punctually at certain days of treatment upon the order of the doctor who is performing the treatment for a respective patient. The order is based on an approximate calculation of the seed requirement for the patient. The calculation is based on the estimation of the prostate volume via medical image data that has been established, typically, weeks before the actual treatment is performed. However, one problem with this estimation of the prostate volume is that the volume of the prostate can change in the time leading up to the date of treatment.
In practice, there is a considerable risk with regard to the fact that, on the day for the treatment, there are not enough similar seeds (e.g., dosage, half-life period, etc.) readily available for the patient. If there is a shortage of seeds, then the treatment has to be aborted. Unfortunately, this may only be discovered when the patient is in the state of narcosis, the prostate having been newly measured with an ultrasonic probe, and the time-related dosage planning having been carried out.
In addition, the seeds are expensive. They simply cannot be returned to a supplier and, at the present time, they cannot be used for other patients for treatment at a later date. If there are not enough seeds available, then all of the seeds are wasted because the operation cannot be performed. If there are too many seeds, then all of the non-placed seeds are wasted because they cannot be used for further treatment purposes. This is particularly disadvantageous because the very expensive palladium seeds have a short half-life period of just under 3 weeks. The inability to use various dosage values is therefore a financial disadvantage for the patient and for the doct
Jojumarie Intelligente Instrumente GmbH
Kenyon & Kenyon
Veniaminov Nikita R
Winakur Eric F.
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