X-ray or gamma ray systems or devices – Specific application – Absorption
Reexamination Certificate
2001-06-01
2002-05-07
Porta, David P. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Absorption
C378S009000
Reexamination Certificate
active
06385288
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radiotherapy apparatus. More particularly, the invention is directed to a radiotherapy apparatus, which can be controlled based on a radiotherapy plan made by referring to a CT image obtained from an integrally provided CT device.
2. Description of the Related Art
With regard to currently practiced radiotherapy, a treatment is generally carried out by operating the CT device, a therapy planning device, a patient positioning device including a bed, and a radioactive ray irradiating device in linkage. Specifically, the CT device is used to form a CT image regarding the affected part of a patient by picking up the image thereof; the therapy planning device to create setting information for each device involved in radioactive ray irradiation according to each case by referring to a three-dimensional image obtained from the CT device; and the radioactive ray irradiating device to treat a disease, such as a tumor or the like, present in the body of the patient by irradiating a diseased part with radioactive rays, e.g., X-rays or electron beams. Usually, the combination of the patient positioning device and the radioactive ray irradiating device is referred to as a radiotherapy apparatus.
Conventionally, the CT device and the radioactive ray irradiating device have been installed in places away from each other, and separately operated. However, for the purpose of enhancing operability and therapy performance by increasing linkage among the devices involved in radiotherapy, and reducing overall costs, requests have been made to integrate such devices. To meet these demands, efforts have been made to develop an apparatus, which includes, for example, a linear acceleration CT disclosed in Japanese Patent Application Laid-Open No. 1984-000076, and a tomographic therapy device disclosed in U.S. Pat. No. 5548627.
FIG. 6
is a schematic sectional view of the constitution of the above-noted tomographic therapy device, specifically showing a case where the portion of a device main body is seen from the foot or head side of a patient. In
FIG. 6
, a reference numeral
10
.
1
denotes a patient to be treated;
102
an affected part of the patient
101
;
103
a bed for the patient
101
;
104
an X-ray source for CT;
105
an X-ray beam for CT, radiating from the CT X-ray source
104
;
106
an X-ray detector for CT;
107
a radioactive ray source for therapy;
108
a collimator; and
109
a radiation beam for therapy, radiating from the therapy radioactive ray source
107
. The CT X-ray source
104
, the CT X-ray detector
106
, the therapy radioactive ray source
107
and the collimator
108
are mounted on the same endless rotating mechanism. A reference numeral
110
denotes a geometrical center axis. The CT X-ray source
104
and the therapy radioactive ray source
107
are secured to the endless rotating mechanism in such a way as to be separated from each other by 90° seen from the center axis
110
. A reference numeral
111
denotes an inner wall portion inhibited from being rotated;
112
an outer wall portion similarly inhibited from being rotated; and
113
a device main body including the bed
103
, the CT X-ray source
104
, the CT X-ray detector
106
, the therapy radioactive ray source
107
, the collimator
108
, the inner and outer wall portions
111
and
112
, and other members, not shown. A reference numeral
114
denotes an image processing computer for forming a CT image regarding an affected part or the like, and creating control information regarding the device main body
113
by referring to the CT image; and
115
a therapy control computer for controlling each device involved in the execution of radiotherapy based on the control information. Interconnections are made between the computers, and between the computers and the above devices by a not-shown network, and information is transferred around by an analog or digital signal.
Now, the typical structures of a radiotherapy apparatus and a CT device developed and made available in the conventional art are described. The radiotherapy apparatus is constructed in such a manner that a gantry head as a beam radiation portion is provided in a gantry installed as an arm-shaped supporting frame, and this gantry is mounted on a rotating mechanism provided in a device main body fixed in a therapy room. The CT device is constructed in such a manner that inside a cylindrical image pickup device, into which a bed carrying a patient can be inserted, an X-ray tube and an X-ray detector are provided symmetrically to the center axis of the cylindrical body, and a rotating mechanism is provided in a device main body for rotating the cylindrical body around the patient. The X-ray detector provided in the CT device comprises a row of detecting elements disposed in an arc shape, and can pick up the image of one section by one rotation. The parallel arrangement of such a plurality of detecting elements also enables multi-slicing to be realized, which simultaneously picks up a plurality of sections by one rotation.
Next, the operation of the tomographic therapy device shown in
FIG. 6
is described.
After the patient
101
is secured to the bed
103
, X-rays radiate from the CT X-ray source
104
while the endless rotating mechanism is rotated. Then, by using the CT X-ray detector
106
to detect the X-rays passed through the patient
101
, image pickup data is obtained regarding one section of the affected part of the patient
101
. The image processing computer
114
receives a signal regarding the image pickup data outputted from the CT X-ray detector
106
, and forms a CT image of the affected part for each rotation of the endless rotating mechanism. When necessary, this process is repeated to form a three-dimensional image. Then, based on the formed CT image, the image processing computer
114
creates control information to generate a therapy radiation beam
109
necessary for realizing proper radiotherapy. In the described tomographic therapy device, the therapy radiation beam
109
is generated while the endless rotating mechanism is rotated as in the case of CT photographing. Accordingly, control information is created in such a way as to optimize setting regarding the opening state or the like of the collimator
108
for each position on a rotational path of the therapy radioactive ray source
107
.
The control information thus created is then sent as therapy plan information to the therapy control computer
115
. Based on the provided therapy plan, and according to the rotation of the endless rotating mechanism, the therapy control computer
115
executes radiotherapy by converging radioactive rays radiating from the therapy radioactive ray source
107
, by the collimator
108
, to match the shape of the patient
101
. When the endless rotating mechanism disposed between these wall portions or each device mounted on the endless rotating mechanism is rotated, the presence of the inner and outer wall portions
111
and
112
can prevent the clashing of such a rotating object with the patient
101
, the bed
103
or other external objects.
However, some problems have been inherent in the foregoing constitution of the tomographic therapy device made available as the radiotherapy apparatus in the conventional art. Specifically, the integrated arrangement of the CT device and the radioactive ray irradiating device on the same endless rotating mechanism has resulted in the increases in weight and volume of the rotating mechanism, creating the mechanical difficulty of achieving high-speed rotation necessary for the CT device.
To rotate the radioactive ray irradiating device at a high speed as in the case of the CT device, it is essential to achieve high-speed control at the radioactive irradiating device side. Particularly in the case of the collimator for mechanically controlling a field of irradiation, there has been a difficulty of changing each setting at a high speed according to a rotational angle.
Furthermore, since the therapy radioactive ra
Gemmell Elizabeth
Mitsubishi Denki & Kabushiki Kaisha
Porta David P.
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