Drug – bio-affecting and body treating compositions – Immunoglobulin – antiserum – antibody – or antibody fragment,... – Binds bacterium or component thereof or substance produced...
Reexamination Certificate
1998-09-22
2001-05-15
Jones, Dameron L. (Department: 1616)
Drug, bio-affecting and body treating compositions
Immunoglobulin, antiserum, antibody, or antibody fragment,...
Binds bacterium or component thereof or substance produced...
Reexamination Certificate
active
06231858
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bolus used closely contacting with a human body to correct distribution of absorbed dose in radiotherapy, and particularly to a disposable bolus.
2. Description of the Prior Art
Irradiation of rays such as X-rays, &ggr;-rays, and electron rays to a human body has been widely used for therapy against disease such as cancer. When the rays are irradiated on material, generally, dose of the rays decreases with depth, but the dose of the scattering rays whose directions are various increases. Therefore, the dose distribution of rays decreases exponentially with depth as shown in FIG.
6
and FIG.
7
. But in rays with high energy the recoiling electrons and/or scattering rays have the components of forward direction mainly, and side scattering rays decrease. Therefore, the dose of rays becomes the greatest at a certain depth compared with surface dose, and after that the dose of rays decreases exponentially with depth as shown in FIG.
6
and FIG.
7
. In therapy to treat the effect of these rays on human skin, the therapy sometimes causes adverse effects because of irradiation of unnecessary rays to normal tissues other than lesions.
For example, assuming that there is a focus under the skin surface in the position of 5 mm as shown in FIG.
1
. If rays whose absorbed dose serves as the maximum under the skin surface in the position of 10 mm are irradiated to this focus to cure the focus, the unnecessary and excess rays are irradiated to normal tissues other than the focus. Especially, in the position of 10 mm under the skin surface the absorbed dose is the greatest, therefore it is risky to cause this part to accompany radiation damage. The bolus has a function to control the dose distribution of rays to irradiate the greatest absorbed dose to the focus. The bolus is used by making it intervene between an irradiation apparatus and a human body as shown in FIG.
2
. Using a bolus as mentioned above, it is possible to cure lesions by irradiating a required therapeutic dose of rays to lesions efficiently.
If radiotherapy is performed to a tumor in the brain as shown in
FIG. 3A
, the dose distribution of rays in the brain is a spherical distribution reflecting an outward form of a head. In this situation, the dose distribution of the greatest absorbed dose is also a spherical distribution to the tumor which have a plate-like form as shown in FIG.
3
A. Therefore, it is very dangerous that the greatest absorbed dose is irradiated to a part except the tumor as shown in FIG.
1
. Here using the bolus which has a form fitted to an outward form of a head as shown in
FIG. 3B
, it is possible to correct the spherical distribution of rays.
Generally, a practically usable bolus must satisfy at least the following properties and conditions:
1. It is a substance equivalent to human body tissue.
2. It is homogeneous.
3. It has excellent plasticity, appropriate resilience, and excellent form-compatibility and adhesiveness to a living body.
4. It is non-toxic.
5. There are no changes in energy, etc.
6. It has even thickness.
7. It does not contain air.
Moreover, it is desirable to have the transparency in addition to the above properties and conditions. Although the expression “equivalent to human body tissue” means in a strict manner that the atomic composition is the same as that of a human body, it means in this context that properties in terms of absorption and scattering of rays are the same as those of substantial tissue.
Plastics, paraffin, synthetic rubbers, silicone, water, and the like have been used as bolus materials up to date.
SUMMARY OF THE INVENTION
Recently, since bacterial and viral infections in the hospital via medical apparatus and instruments have become a serious problem and in light of HIV infection, a demand for disposable instruments that are disposed after having been used only once has been further increasing.
However, since the price of conventional boluses using plastics, paraffin, silicone, or synthetic rubbers as their base material is very expensive and although the boluses are based on the size, and they must be disposed of as so-called industrial wastes because the used boluses can not be disposed of easily without treatment. Therefore, it is unrealistic to dispose the boluses after only one use.
Using the above-mentioned boluses, there are problems with respect to time and costs, because the boluses according to the prior art technology had to be used repeatedly and the boluses must be disinfected to maintain cleanliness before reuse. Moreover, repeated use may give an uncomfortable feeling to persons undergoing diagnosis in terms of cleanliness.
When water is used as bolus, although water itself can be easily disposed, containers enclosing water can not be easily disposed. In addition, there is a problem in the manufacturing technique that makes it difficult to enclose water.
The object of the present invention is to provide a bolus that satisfies various properties required for a bolus, and is disposable, can be prepared more inexpensively than conventional ones, and is excellent in terms of cleanliness and processability to solve the above-mentioned problems.
An invention of this application relates to preparation method of boluses for radiotherapy, which are inexpensive, disposable, and excellent in terms of processability, and the above objects in this invention are achieved with hydro gels using specific natural organic polymer gelatinizing preparations
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Ito et al, Radioisotopes, vol. 47, pp. 19-28, States of Water Molecules of Hydro Geiseidadated from 0-Positronium Lifetime measurement (English translation) Jan. 1998.*
Matsubashi et al, Food Irradiat. Jpn, vol. 21, No. 1-2, pp. 29-42, Effects of Gamma Irradiation on Melting Point of Gel of Agar & Carrageenan (English translation) 1986.*
Matsuhashi et al (1986), Food Irradiat. Jpn., 21 (1-2), 29-42, “Effects of Gamma Irradiation on Melting Point of Gel of Agar and Carrageenan.” .*
Ito et al (Jan., 1998), Radioisotopes, vol. 47, No. 1, pp. 19-28, “States of water molecules of hydro gels elucidated from 0-positronium”.*
Singh et al (1980), J. of Scientific and Industrial research, vol. 39, pp. 162-171, “Polymeric Hydrogels: Preparation and Biomedical Applications”.*
Nakamura (1998), Res. Rep. Fac. Eng., Mie Univ, 23, 149-150, “Studieson Functional Hydro-Gels Preparation and its Characterization in the course of volume Phase transition.”*
Collett et al (1980 (RECD 1981)), J. Pharm. Pharmacol. 32 (suppl), 6P, “The Effects of Some Solutes on the Hydration of Poly (HEMA) Hydrogels Prepared by Chemical of Radiation procedures”.
Ebihara Fumitaka
Hatakeyama Kazunori
Izeki Shin
Koga Yoshinori
Birch & Stewart Kolasch & Birch, LLP
Jones Dameron L.
Mochida Corporation
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