X-ray or gamma ray systems or devices – Specific application – Absorption
Reexamination Certificate
2000-05-04
2002-08-20
Church, Craig E. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Absorption
Reexamination Certificate
active
06438203
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to radiotherapy devices, and more particularly to a rotary whole-body radiotherapy device with multiple radioactive sources.
BACKGROUND OF THE INVENTION
Rotary whole-body radiotherapy device with multiple radioactive sources works on the principle of focusing while rotating. The multiple radioactive sources installed in the rotary source body are made to rotate in a family of coaxial conical planes, and directing at the common focus point coincident with the common vertex of the conical planes. As a result, the lesion tissue located at the common focus point is killed, while the healthy tissue are spared by receiving only instant and harmless radiation. In the view of nuclear physics, the dose of the radioactive source at the focus point is in reverse proportion to the square of the distance between the radioactive source and the focus point. On the one hand, the distance from the center of the radioactive source to the focus point should be as short as possible, and on the other hand, to implement rotary radiation to disease site located at any place of the patient, there should be enough space from the exit of the collimator to the body surface of the patient. In the prior art, the radioactive sources are uniformly distributed on the rotary cylindrical source body which rotates in full angle range of 360°. Such an arrangement is known from CN Patent No. 96213589.5, which discloses a rotary whole-body radiotherapy device with a source body of hollow cylindrical shape. Take the plane which passes the focus point and perpendicular to the center line of the hollow cylinder as the datum plane, the radioactive sources are arranged in several groups on the cylindrical plane from latitudes 3° to 48° relative to the reference plane. On the surface plane of the cylindrical source body, the groups of channels are distributed uniformly along the circumference as viewed from the axial direction, they can be either spaced equidistantly in parallel, or ascending one line by each group. The collimators and the shielding rods are distributed in the same pattern as the radioactive sources, and as a result, beam channels are formed. Since the radioactive sources and the collimators are distributed within a full angle range of 360° along the circumference, the internal radius of the hollow cylinder should be no less than the distance from the exit of the collimators to the focus point is equal to. In order to implement radiation to the disease site at any place of the patient, said internal radius should be greater than the width of a human body, i.e., the distance from the exit of the collimators to the focus point should be greater than 48 centimeters. Therefore, in the prior art device, the radioactive sources have high total radiation activity, expensive production cost, low utility efficiency, and require critical shielding. As a result, the device is bulky in volume, heavy in weight, and high in production cost.
SUMMARY OF THE INVENTION
The primary objective of the present invention is to provide a whole-body radiotherapy device with multiple radioactive sources renovated in configuration, so as to shorten the distance (referred to as source-focus-distance) from the radioactive sources to the focus point, and consequently improve the utility efficiency of the radioactive sources, reduce the volume and weight of the device.
In accordance with the present invention, there is provided a whole-body radiotherapy device with multiple radioactive sources, comprising rotary fixing frame, source body and collimator body whose rotating axis is parallel to the longitudinal axis of the treatment couch. Multiple radioactive sources and their. beam channel are distributed in said source body, and the beam from said radioactive sources focus on the common focus point through said beam channel. The collimators are located in the collimator body, and they have the same distribution pattern as the radioactive sources. The source body and the collimator body are fixed on the rotary fixing frame and can be made to rotate around the rotating axis. Taking the plane which passes the common focus point and perpendicular to the rotating axis as a datum plane, said datum plane is made to rotate around the line which passes the common focus point and perpendicular to the rotating axis. As a result, a family of planes are formed which are defined as radial sectional planes. In said radial sectional planes, radioactive sources and their beam channels are located within a fan shaped area whose included angle is less than 90°.
Since the radioactive sources and their beam channels are located within a fan shaped area whose included angle is less than 90°, instead of distributing in full angle range of 360° in said radial section planes, the radioactive sources and their beam channels can be limited to the region of a very narrow fan shape. Making the inner rotary radius of the collimator body longer than half width of the human body, the rotary radiotherapy at any place of the human body can be implemented by positioning the disease site at the focus point, and selecting the incidence angle and rotary range of the beam accordingly, instead of rotating in full angle range of 360°. Therefore, the contradictory between the demands of a large treatment space and a short source-focus-distance is successfully solved. With the guarantee of, retaining enough treatment space for the whole body, the source-focus-distance is greatly reduced. As a result, the total radiation activity and the production cost of the sources are greatly reduced, the utility efficiency of the radioactive sources is improved, the volume size, the weight and the production cost of the device are reduced. Consequently, significant economic effect and social effect are achieved.
REFERENCES:
patent: 5894503 (1999-04-01), Shepherd et al.
Guangwu Liu
Shipeng Song
Church Craig E.
Shen Zhen Hyper Technology Incorporation
Westman Champlin & Kelly P.A.
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