JPH04317634A - Radiation treating system - Google Patents

Abstract

PURPOSE:To improve image quality and to shorten the time for imaging by forming radiations for image pickup to a slit-shaped fan beam spreading in one direction to a patient, scanning the beams in the direction perpendicular to one direction, outputting a radiation detection signal and constituting the linacgraphy of the lesion of the patient in accordance with this output. CONSTITUTION:A collimator setting section 12 feed backs the position detection signal L3 from a position detector 11 in accordance with the command from a main operation controller 21 and automatically controls the position of the collimator 3. The X-rays R generated from an X-ray irradiation section 2a at this time are throttled by the collimator 3 to the fan beam which is projected through the lesion 7 to a scintillator 9. The scintillator 9 outputs the radiation detection signal S proportional to the projection X-ray intensity. A data collector 15 makes AD conversion of the radiation detection signal S at a high speed after amplification and transmits the signal to a computer 19 for image processing by direct memory access transfer.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a radiation therapy device that uses medical linac radiation to align the center of an affected area with the isocenter, and in particular improves the image quality of linac photography, which takes fluoroscopic images of the affected area, and improves the imaging time. The present invention relates to a radiation therapy device that shortens the time required to achieve affected area positioning accuracy and reduces costs.

0002

[Prior Art] Conventionally, as a radiation therapy device, X
X-ray therapy devices using radiation, electronic linacs using high-frequency electric fields, betatrons using alternating magnetic fields, and cobalt therapy devices using radioisotopes as radiation sources are known.

[0003] When treating an affected area using such a radiotherapy device, it is necessary to know in advance the position and shape of the affected area within the patient's body in order to determine the irradiation direction and irradiation field of therapeutic radiation to the patient. be. Therefore, linacgraphy (a fluoroscopic image of the affected area) is obtained using an X-ray CT, a simulator, etc., or by generating imaging radiation with a lower dose and lower energy than therapeutic radiation from the same X-ray source, The patient is positioned so that the center of the affected area and the isocenter of therapeutic radiation coincide.

[0004] FIG. 9 is a side view showing a conventional radiation therapy apparatus that is capable of obtaining linacography using imaging radiation, and here shows a case where X-rays are used as the radiation. In the figure, numeral 1 denotes a fixed pedestal of the radiation generating apparatus, and 2 denotes a rotating pedestal that is pivotally supported by the fixed pedestal 1 and rotates around the X axis (body axis of the patient). Reference numeral 2a denotes an X-ray irradiation unit provided at one end of the rotating frame 2, which directs X-rays R corresponding to small-dose, low-energy imaging radiation or large-dose, high-energy therapeutic radiation, for example, in the Z-axis direction. Occurs selectively. 3 is the X-ray R emitted from the X-ray irradiation section 2a
4 is the X-ray R
This is a collimator that determines the irradiation field in the Y-axis direction.

Reference numeral 5 denotes a treatment table placed opposite the X-ray irradiation section 2a, and is positioned by electric drive control. Reference numeral 6 indicates a patient placed and fixed on the treatment table 5, 7 indicates an affected area to be treated within the patient 6, and 8 indicates an X-ray film arranged to receive the X-rays R transmitted through the affected area 7. Figure 10 shows the affected area 7.
FIG. 3 is a plan view showing the relationship between collimators 3 and 4 and the affected area 7 when photographing.
A wide rectangular area including the area is determined as the irradiation field.

Next, referring to FIG. 10, a description will be given of the linac imaging acquisition operation by the conventional radiation therapy apparatus shown in FIG. First, as shown in Figure 9,
The rotating pedestal 2 is positioned so that the radiation direction is the Z-axis direction, and the treatment table 5 is positioned so that the affected area 7 is located directly below the X-ray irradiation section 2a, and so that it faces the X-ray irradiation section 2a. Then, the X-ray film 8 is positioned below the treatment table 5. Then, X-rays R corresponding to imaging radiation are generated from the X-ray irradiation section 2a.

At this time, since the X-rays R are narrowed down to the rectangular irradiation field shown in FIG. 10, if the positioning of the affected area 7 is approximately accurate, the affected area 7 will be imaged at the center of the X-ray film 8. By referring to the linac graphics thus obtained, it can be confirmed whether the center of the affected area 7 is accurately positioned at the isocenter. If it is determined from Linacgraphy that the positioning of the affected area 7 has not been performed accurately, move the treatment table 5 and position the affected area 7 again, and repeat the same radiographs until accurate positioning is confirmed. repeat.

[0008] In this way, after obtaining a linac graph of the affected area 7 using X-rays R, which is radiation for imaging, and confirming that there is no error in positioning the affected area 7, X-rays R, which corresponds to therapeutic radiation, are The affected area 7 is actually treated by causing the disease to occur. At this time, the X-rays R serving as therapeutic radiation are sufficiently focused to match the shape of the affected area so as not to damage normal tissue. The above is a commonly used protocol.

However, when photographing the affected area 7, as shown in FIG.
Since X-rays R are irradiated in a wide rectangular irradiation field like this, the influence of scattered radiation on the irradiated area becomes large, making it impossible to obtain clear linac graphics. In general, the dose D(d) at a point of depth d in the heterogeneous material within the radiation field
teeth,

0010

[Math 1]

It is expressed as: However, in formula ■, Dp
(d) is the primary radiation dose, Ds(d) is the scattered radiation dose, F
1 and F2 are correction coefficients depending on the size of the irradiation field. Furthermore, in an apparatus using X-ray R as a radiation source, such as a medical linac, it is known that Ds(d)F2 in equation (2) becomes larger as the irradiation field becomes larger. Therefore, in this case, the influence of scattered radiation at imaging points around the affected area increases, and the contrast of linac photography becomes unclear.

Furthermore, when the X-ray film 8 is used, it takes time to convert it into an image (developing it), so the treatment table 5
The position of the patient 6 above may change, and the affected area 7 may move from its position on the X-ray film 8 when referring to the linac graph, making it difficult to confirm positioning with high precision. .

On the other hand, in order to obtain a clear image of the affected area 7,
Even if a line CT or simulator (not shown) is used separately,
Similarly, imaging takes time and leads to increased costs. Furthermore, the position of the affected area 7 on the simulator is different from the position on the treatment table 5, and errors occur due to the limits of the mechanical positioning accuracy of the simulator, making highly accurate positioning difficult. Therefore, X becomes therapeutic radiation.
There is a risk that the ray R may not be accurately irradiated to the affected area 7 and normal tissues other than the affected area 7 may also be irradiated.

[0014]

[Problems to be Solved by the Invention] As described above, in the conventional radiation therapy apparatus, when the X-ray irradiation section 2a is shared to generate imaging radiation and therapeutic radiation, it is necessary to use a wide irradiation field when imaging the affected area 7. Because it generates radiation for imaging, clear linac photography cannot be obtained, and
There was a problem in that it took time to develop the X-ray film 8, and the affected area 7 could not be positioned accurately.

[0015] Furthermore, when an X-ray CT or simulator is used, not only does it lead to an increase in cost, but it also takes time to obtain the linac graph, so there is a problem that the affected area 7 cannot be accurately positioned. there were.

[0016] This invention was made to solve the above-mentioned problems, and provides radiation therapy that improves the image quality of linac photography, shortens the imaging time, improves the accuracy of positioning the affected area, and reduces costs. The purpose is to obtain equipment.

[0017]

[Means for Solving the Problems] A radiation therapy apparatus according to the present invention includes a radiation irradiation section that selectively generates radiation serving as therapeutic radiation or imaging radiation toward a patient on a treatment table; a collimator that determines the irradiation field of the patient, a collimator control unit that converts the imaging radiation into a slit-shaped fan beam that spreads in one direction toward the patient, and scans it in a direction perpendicular to the one direction; The system is equipped with a radiation detector that detects the radiation detected and outputs a radiation detection signal, and a computer that configures linac photography of the affected area of the patient based on the radiation detection signal.

The radiation therapy apparatus according to the present invention also includes a drive control unit for positioning the treatment table so that the isocenter of the therapeutic radiation coincides with the center of the affected area based on the position of the affected area on the linac graph. It is also equipped with additional features.

[0019]

[Operation] In the present invention, imaging radiation consisting of a fan beam is scanned, and linac graphics with high resolution and good contrast are obtained in a short time based on radiation detection signals from a radiation detector.

Furthermore, in the present invention, the center of the affected area is positioned with respect to the isocenter of therapeutic radiation automatically and with high precision based on linac photography. or,
In this invention, generation of therapeutic radiation is interrupted when it is determined from a real-time radiation detection signal based on therapeutic radiation that the irradiation field of therapeutic radiation is larger than the affected area by more than a tolerance value.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a side view showing the overall configuration of the device in FIG. 1, and FIG. 3 is a front view of FIG. 2, with 1 to 7 being the same as described above. . Note that in FIG. 1, the collimator 4 is not shown.

In this case, the X-rays R as imaging radiation are focused only in the X-axis direction and become a slit-shaped fan beam that spreads in one direction (Y-axis direction) toward the affected area 7 of the patient 6. There is. Reference numeral 9 denotes an X-ray detector (scintillator) that detects the X-rays R that have passed through the affected area 7 and outputs an X-ray detection signal S, and is disposed opposite to the X-ray irradiation section 2a. or,
The scintillator 9 has a fan shape corresponding to the fan beam shape of the X-ray R as shown in FIG. 3, and is composed of, for example, 100 or more channels of elements in order to obtain the required resolution.

10 is a motor that drives the collimator 3;
A position detector 1 outputs a position detection signal L3 of the collimator 3 based on the rotational position of the motor 10. Reference numeral 12 denotes a collimator control unit for feeding back the position detection signal L3 to drive and control the collimator 3, and converts the X-ray R serving as the imaging radiation into the above-mentioned fan beam, and
Scanning is performed in the X-axis direction (corresponding to the body axis of the patient 6) perpendicular to the axial direction.

13 is a motor that drives the scintillator 9;
14 is a scintillator 9 based on the rotational position of the motor 13.
A position detector 15 outputs a position detection signal L9, and a data acquisition device 15 amplifies and AD converts the radiation detection signal S.
16 is a motor that drives the treatment table 5, 17 is a position detector that outputs a position detection signal L5 of the treatment table 5 based on the rotational position of the motor 16, and 18 is a position detection signal L9 and L5. This is a drive control unit for controlling the scintillator 9 and the treatment table 5 by feeding back the information. Although the drive control section 18 is shown here as one block, the treatment table 5 and scintillator 9 may be controlled separately by separate drive control sections.

Reference numeral 19 denotes a computer 20 for configuring linac photography of the affected area 7 based on the radiation detection signal S via the DAS 15 and for controlling the entire system.
is a monitor for displaying images belonging to the computer 19. 21 is a main operation controller connected to the computer 19, which drives and controls the treatment table 5 and scintillator 9 via the computer 19, and also drives and controls the collimator 3 via the collimator control section 12.

Next, while referring to FIGS. 4 to 8, FIGS.
The operation of the embodiment of the present invention shown in FIG. 3 will be described. The main operating controller 21 controls the operation of the treatment system and
In addition to controlling the radiation source, the motor 10 is driven via the collimator control section 12 to control the positioning of the collimator 3.

Further, the collimator control unit 12 automatically controls the position of the collimator 3 by feeding back the position detection signal L3 from the position detector 11 in accordance with a command from the main operation controller 21, and for example, controls the position of the collimator 3. During imaging, X-rays R, which serve as imaging radiation, are made into a fan beam in the Y-axis direction and scanned in the X-axis direction.

At this time, the X generated from the X-ray irradiation section 2a
The line R is narrowed down by the collimator 3 to become a fan beam, which passes through the affected area 7 and is projected onto the scintillator 9. As a result, the scintillator 9 outputs a radiation detection signal S proportional to the projected X-ray intensity, and the DAS 15 amplifies the radiation detection signal S, performs high-speed AD conversion, and uses direct memory access (DMA) transfer for image processing. The data is transmitted to the computer 19 of.

[0029] The drive control section 18 also includes a computer 19.
According to a command from the scintillator 9, the position detection signal L9 from the position detector 14 is fed back, and the scintillator 9 is automatically driven and controlled via the motor 13. Thereby, the scintillator 9 is scan-controlled in the X-axis direction as indicated by the arrow in FIG. 4 in response to the scanning of the X-rays R serving as imaging radiation.

FIG. 5 is an explanatory diagram showing in detail the positional relationship between the scanning area of the X-ray R, the affected area 7, and the isocenter.
is the irradiation field of X-ray R at the start of scanning, Rs' is the irradiation field at the end of scanning, 9' is the scintillator position at the end of scanning, Tc is the center of the affected area, Ic is the isocenter, x
0 is the fan beam width in the X-axis direction, y1 is the fan beam length in the Y-axis direction, x1 is the scanning drive amount in the X-axis direction, and xi and yi are the X-axis and Y-axis directions between the affected area center Tc and isocenter Ic. is the distance of each coordinate.

First, at the start of scanning, the collimator 3
is driven and controlled to generate X-rays R having an irradiation field Rs of a rectangular area x0×y1. And the collimator control section 12
And under the control of the drive control unit 18, the irradiation field Rs and the scintillator 9 are scanned as indicated by the broken line arrow, and the scanning is performed to the positions Rs' and 9' indicated by the dashed-dotted line, and the imaging is completed. Thereby, projection data of the scanning area x1×y1 is obtained as the radiation detection signal S from the scintillator 9.

The computer 19 scans the scanning area x1×y1
The radiation detection signal S from the radiation detection signal S is image-processed, a linac graph of the affected area 7 and surrounding tissues of the affected area is calculated in a short time, and this is displayed on the monitor 20. At this time, since the X-rays R irradiated to the affected area 7 are fan beams, the influence of scattered radiation is small, and the image quality of linac photography is improved. Therefore, it is possible to confirm with high precision whether the center of the affected area Tc and the isocenter Ic match on the XY plane.

Next, as shown in FIGS. 6 and 7, the rotary pedestal 2 is rotated 90 degrees, and the patient 6 is irradiated with X-rays R consisting of a fan beam spread in the Z-axis direction in the Y-axis direction. A linac graph is constructed by scanning in the X-axis direction in the same manner as described above. As a result, as shown in FIG. 8, the shape of the affected area 7 in the depth (Z-axis) direction and the Z-axis coordinate distance Zi between the affected area center Tc and isocenter Ic are calculated.

Generally, the patient 6 is fixed and positioned on the treatment table 5 each time treatment is performed, but the relative positional relationship between the treatment table 5 and the patient 6 differs each time, and the patient 6's delicate Due to body positional fluctuations, it has been difficult to accurately align the center of the affected area Tc with the isocenter Ic.

However, in this case, the distance between the center of the affected area Tc and the isocenter Ic can be instantaneously determined from the XYZ coordinate distances xi, yi, and Zi by the calculation of the computer 19. Therefore, when the distance between the affected area center Tc and the isocenter Ic is large, the computer 19
8, the treatment table 5 is moved in three axial directions via the motor 16, and accurate positioning is automatically performed so that the center of the affected area Tc and the isocenter Ic coincide.

In this way, the center of the affected area Tc is the isocenter Ic.
After being positioned, the affected area 7 is treated by generating X-rays R serving as therapeutic radiation from the X-ray irradiation unit 2a. At this time, the computer 19 can detect the size of the irradiation field actually being treated in real time by scanning the scintillator 9 according to the irradiation field of the X-rays R serving as the therapeutic radiation.

The computer 19 determines the irradiation field from the radiation detection signal S obtained during treatment, superimposes and compares this irradiation field with the pre-calculated shape of the affected area 7, and determines whether the irradiation field is within the allowable value from the affected area 7. When it is determined that it is larger than
An interlock signal is sent to the main operation controller 21, and the X-ray R
stop the occurrence of As a result, even if the isocenter Ic is more than the allowable distance from the center of the affected area Tc due to some mistake, or if the size of the irradiation field during treatment is inappropriate, the X-ray R can be interrupted immediately and an accident can occur. can be prevented, improving safety.

In this way, under the control of the main operation controller 21 and the computer 19, the collimator 3 and the scintillator 9
By automatically positioning and driving the treatment table 5 and generating radiation for imaging from the X-ray irradiation unit 2a that generates radiation for treatment, a separate device is not required and costs can be reduced.

In the above embodiment, the scintillator 9 was used as the radiation detector, but an ionization chamber, a semiconductor X-ray detector, etc. may also be used. Furthermore, although the scintillator 9 is made into a line shape corresponding to the fan beam and scanned in correspondence with the scanning of the fan beam, if the scintillator 9 is made into a planar shape that covers the scanning area of the X-ray R, there is no need to scan the scintillator 9. do not have.

[0040]

As described above, according to the present invention, there is provided a radiation irradiation section that selectively generates radiation serving as therapeutic radiation or imaging radiation toward a patient on a treatment table, and a radiation irradiation field for the patient. a collimator that determines the imaging radiation, a collimator control unit that converts the imaging radiation into a slit-shaped fan beam that spreads in one direction toward the patient, and scans the radiation in a direction perpendicular to the one direction; The system is equipped with a radiation detector that detects radiation and outputs a radiation detection signal, and a computer that configures linac photography of the patient's affected area based on the radiation detection signal, thereby improving the image quality of linac photography and shortening the imaging time. This has the effect of providing a radiation therapy apparatus that achieves improved accuracy in positioning the affected area and reduced costs.

Further, according to the present invention, the treatment table further includes a drive control unit for positioning the treatment table so that the isocenter of the therapeutic radiation and the center of the affected area coincide with each other based on the affected area position on the linac graph, The center of the affected area is positioned automatically and with high precision relative to the isocenter of therapeutic radiation, improving the image quality of linac photography and shortening the imaging time, improving the accuracy of positioning the affected area and reducing costs. This has the advantage of being a radiation therapy device.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a side view showing the entire device of FIG. 1;

FIG. 3 is a front view of FIG. 2;

FIG. 4 is an explanatory diagram showing the scanning direction of the collimator and scintillator in FIG. 2;

FIG. 5 is an explanatory diagram showing the positional relationship between the irradiation field area, the center of the affected area, and the isocenter in the scanning state of FIG. 4;

FIG. 6 is a front view showing a state in which the rotary frame is rotated by 90 degrees from the state in FIG. 3;

FIG. 7 is a plan view showing the scanning direction of the collimator and scintillator in FIG. 6;

8 is an explanatory diagram showing the positional relationship between the irradiation field region, the center of the affected area, and the isocenter in the scanning state of FIG. 7; FIG.

FIG. 9 is a side view showing a conventional radiation therapy apparatus.

FIG. 10 is an explanatory diagram showing an irradiation field during X-ray imaging in FIG. 9;

[Explanation of symbols]

2 X-ray irradiation unit 3 Collimator 5 Treatment table 6 Patient 7 Affected area 9 Scintillator (radiation detector) 12
Collimator control unit 18 Drive control unit 19 Computer R X-ray Rs Irradiation field S Radiation detection signal Ic Isocenter Tc Center of affected area

Claims (4)

[Claims] 1. A radiation irradiation unit that selectively generates radiation serving as therapeutic radiation or imaging radiation toward a patient on a treatment table, a collimator that determines an irradiation field of the radiation to the patient, and the imaging device. a collimator control unit for converting radiation into a slit-shaped fan beam that spreads in one direction toward the patient and scanning in a direction perpendicular to the one direction; A radiation therapy apparatus comprising: a radiation detector that outputs a detection signal; and a computer that configures linac photography of the affected area of the patient based on the radiation detection signal. 2. The radiation therapy apparatus according to claim 1, further comprising a drive control section for scanning the radiation detector in response to scanning of the collimator. 3. The method further comprises a drive control unit for positioning the treatment table so that the isocenter of the therapeutic radiation coincides with the center of the affected area based on the position of the affected area on the linac graph. The radiotherapy apparatus according to claim 1 or claim 2. 4. The computer suspends the generation of the therapeutic radiation when it is determined from the radiation detection signal based on the therapeutic radiation that the irradiation field of the therapeutic radiation is larger than the affected area by more than a tolerance value. The radiation therapy apparatus according to claim 3, characterized in that: