Apparatus and method for compensating for respiratory and patient motion during treatment

The present invention relates to a device for improving the positional accuracy and effectiveness of surgical treatment.

The present invention typically generates devices for improving the accuracy and effectiveness of surgical treatments, more specifically, during treatments, cyclically generating positional data about internal target areas within the patient's body. It relates to grasping the position of the target site to be treated when the first detection device does not operate, and to track the movement of the target site due to breathing or other movements of the patient.

In order to treat a target site, various treatments accurately track the movement of the target site. For example, in radiation therapy and radiosurgery, tissue can be destroyed by an ionized radiation beam that kills cells in the tissue. The problem is that tissue may move during treatment, especially due to the patient's respiratory movements. Such respiratory movements are difficult to track with external sensors. This is because the extent and direction of the patient's internal respiratory movements cannot be visually recognized by conventional imaging devices. The patient's breathing and other movements mean that it is more difficult to concentrate the radiation on the tissue, which can make the treatment less effective and unnecessarily damage the normal tissue. It means that you may receive it.

The radiation beam is typically moved during treatment to allow proper distribution of the radiation dose to the tissue. In conventional systems, the beam is moved along an arc in space. The aim is to give very high doses of radiation only to given tissue, while protecting the surrounding normal tissue as much as possible. Although this radiosurgery technique has been applied to brain tissue with dramatic success, it is still difficult to extend this technique to the outside of the head or to the neck area. The main reason for this difficulty was the problem of accurate target positioning (ie, accurate tracking of target movement). In particular, respiratory movements and movements of other organs and patients make it difficult to track the target tissue with high accuracy, thus providing a high dose of radiation to a given tissue while protecting the surrounding normal tissue. It becomes difficult to achieve the purpose. Moreover, conventional systems can only move the radiation beam along an arc in space and cannot easily track irregular respiratory movements. This is because these respiratory movements do not always occur along the axis of the arc that the radiation beam follows.

Another radiosurgery technique uses a mechanical robotic device with six degrees of freedom to aim a radiation beam, as disclosed in US Pat. No. 5,207,223. This robotic device allows the radiotherapy beam to be accurately positioned in order to direct the oriented therapeutic beam to the target site. U.S. Pat. No. 5,769,861 discloses a neurosurgical navigation method. This method involves discovering immovable targets such as brain tissue, tracking the movement of target organs to the surface of the skin, such as the lungs due to breathing, or the abdominal cavity for externally visible movements. Tracking the movement of internal organs is not an issue. Fiducial (collimation marks) that may be implanted in the human body so that they can be detected by an imaging device are also disclosed, and the fiducial implant is implanted in the bone or organ of the human body. Although this fiducial implant allows the internal structure of the human body to be analyzed, it is not intended to compensate for the movement of target organs that move throughout the respiratory cycle. Therefore, it is desirable to provide a device and a method for compensating for breathing and movement of other patients during radiotherapy, and this is an object of the present invention.

According to the present invention, an internal marker placed on a target organ is combined with one or more external sensors that accurately track the position and movement of a moving target site such as an internal organ, and the patient's breathing or other movement Equipment and methods for compensating for the above are provided. In particular, the position of the internal marker, which is periodically determined by X-rays, may be combined with the position of the external sensor. Since an invasive technique such as X-ray is required to image the internal marker, the internal marker may be imaged periodically. During treatment, an external continuous or real-time sensor, such as an external marker, determines external motion. Thus, the position of the target organ is accurately determined by the position of the internal marker when the internal marker is periodically imaged, and based on the data of the external sensor when the internal marker is not imaged. May be good. The position and movement of the internal marker relative to the external sensor is determined so that the position of the internal marker, and thus the position of the target organ, can be accurately determined by the position of the external sensor. Thus, the location of the organ of interest is accurately determined throughout the course of the medical procedure.

Internal markers can be imaged using a number of imaging devices, including X-rays, nuclear magnetic resonance, ultrasound, and other techniques that can image markers in the patient's body. Alternatively, a three-dimensional ultrasound image can be used instead of each discrete fiducial to determine the position of the internal target site. The position of the external sensor can also be determined using a number of techniques, including infrared imaging, visual imaging, magnetic positioning, breath measurement, and other methods of imaging that allow the imaging of external markers. it can. In addition to using external sensors (ie, external fiducials may not be available), body surfaces that correlate with internal fiducials can also be visually imaged.

Thus, according to the present invention, there is provided an apparatus for treating an internal target site while measuring the patient's respiration and other movements, and optionally compensating for them. This device is a first imaging device for periodically generating position information about an internal target site and continuously position information about one or more external markers attached to the patient's body. It is provided with a second imaging device for generating. The device also includes a processor that receives position information about the internal target site and external sensor readings / measurements to generate a correspondence between the position of the internal target site and an external marker or sensor reading, and an external marker. Alternatively, it is provided with a treatment device that directs the treatment to the position of the target site of the patient based on the sensor reading. A device for compensating the patient's movement during treatment is disclosed, as is a method for compensating the patient's movement.

<figref num="1">It is a drawing which shows the conventional radiotherapy apparatus.</figref><figref num="2">It is a drawing which shows the radiotherapy apparatus in more detail.</figref><figref num="3">It is a drawing which shows the radiotherapy apparatus in more detail.</figref><figref num="4">It is a block diagram which shows the radiotherapy apparatus.</figref><figref num="5">It is a drawing which shows the internal marker on the target organ when the target organ moves.</figref><figref num="6">FIG. 5 shows one or more internal markers attached to a target organ imaged by an X-ray machine.</figref><figref num="7A">It is a drawing which shows the image of the internal marker by this invention.</figref><figref num="7B">It is a drawing which shows the image of the internal marker by this invention.</figref><figref num="7C">It is a drawing which shows the image of the internal marker by this invention.</figref><figref num="7D">It is a drawing which shows the image of the internal marker by this invention.</figref><figref num="8">It is a drawing which shows the internal marker combined with the external marker for tracking the movement of the target area by this invention.</figref><figref num="9A">It is a figure which shows the reduction of the safety seam by this invention.</figref><figref num="9B">It is a figure which shows the reduction of the safety seam by this invention.</figref><figref num="9C">It is a figure which shows the reduction of the safety seam by this invention.</figref><figref num="9D">It is a figure which shows the reduction of the safety seam by this invention.</figref><figref num="10">FIG. 5 is a flow chart showing a method of compensating for breathing and other movements within a radiosurgery device.</figref><figref num="11">It is a flowchart which shows the method of correlating the internal marker and the external marker by this invention.</figref>

The present invention is particularly applicable to devices and methods for compensating for respiration and other movements of a patient during radiation therapy (radiation surgery), and the present invention describes in this regard. However, the devices and methods of the present invention are other types of medical procedures using other types of medical devices that perform biopsy, ablation, ultrasound or other energy focusing instruments positioning or laser beam positioning for laser beam therapy. It also has great practicality. Prior to the description of the present invention, a general radiation surgical apparatus will be described in order to enable a better understanding of the present invention.

1 to 4 show an example of a stereotaxic radiotherapy apparatus 10. The radiotherapy apparatus 10 has a data processor 12 such as a microprocessor and a disk or tape storage unit 13 (FIG. 4) that stores a three-dimensional image of the patient 14. The 3D image, if not yet loaded, is loaded into the data processor and compared with the 3D image obtained during surgery. Three-dimensional images are created by various conventional techniques such as computer tomographic imaging (CAT) scanning or magnetic resonance imaging (MR). The radiotherapy device 10 also has a beam generator 20, which, when activated, emits an ionized beam for aiming surgery directed at the target region 18 (FIG. 2). Aiming surgical ionized beams are strong enough to necrotize the target area. Linear Accelerators Various beam generators, such as preferably X-ray linear accelerators, that generate ionizing radiation or heavy particle beams can be used. Such X-ray beam generators are commercially available. The beam generator is operated by the operator turning on the switch 23 on the control console 24 connected to the beam generator via the cable 22.

The radiotherapy device 10 also has a device that passes a first diagnostic beam 26 and a second diagnostic beam 28 through a previously imaged region by a three-dimensional image. Both diagnostic beams are arranged at predetermined non-zero angles with each other, as shown in the orthogonal state in FIG. Both diagnostic beams are generated by the first X-ray generator 30 and the second X-ray generator 32, respectively. The first and second image receivers 34, 36 receive the diagnostic beams 26, 28 and create an image from the diagnostic beam supplied to the microprocessor 12 (FIG. 4), and the diagnostic image is compared with the 3D image.

The radiotherapy device 10 also has a device that adjusts the relative position of the beam generator 20 and the patient 14 so that the ionized beam is continuously focused on the target region 18. In the radiotherapy apparatus shown in FIG. 1, the position of the beam generator and the patient can be changed with 6 degrees of freedom by the gantry 40 and the movable operating table 38. The position of the beam generator with respect to the patient can also be changed using a processor-controllable robot arm mechanism 46 (Fig. 3) with 6 motion axes. The robot arm mechanism 46 can freely move the beam generator 20 around the patient's body (upward, downward, longitudinally or laterally along the patient's body).

FIG. 4 shows a radiotherapy device equipped with a microprocessor 12, a tape drive 13, a beam generator 20, a robot arm 46 or a gantry 40, an X-ray camera 30, 32, 34, 36, and an operator control console 24 as described above. It is a block diagram of 10. The device 10 may also be provided with a safety interlock 50 to prevent the beam generator 20 from being operated unexpectedly. The device 10 may also be provided with an operator display 48 for tracking the progress of the treatment and controlling the treatment. Further details of the radiotherapy apparatus are disclosed in US Pat. No. 5,207,223, which is owned by the Applicant and incorporated herein by reference.

In order to accurately target the area to be irradiated by radiation therapy or radiation surgery, it is necessary to determine the position where the target is placed during the treatment with high accuracy. Since the brain is fixed to a hard skull, the radiosurgery device is ideally used for the treatment of brain or head tumors. Radiosurgical devices can also be used in other fixed target areas (provided that they do not surround healthy tissue) where the ionized beam can be easily ensured to irradiate the target area. However, if the target is adjacent to the diaphragm, the patient's breathing will move the target during treatment. When the patient breathes or moves during treatment, the lungs and other organs will move. Therefore, it is desired to provide devices and methods for accelerating moving target areas during various therapies, including radiation therapy. The device of the present invention compensates for the movement of the target region caused by the patient's breathing as well as the movement of the target region caused by other movements of the patient.

According to the present invention, external markers and internal markers (landmarks), as described below, are used to determine the location of internally moving target areas, such as internal organs, based on a series of images prior to treatment. The model of the relative movement of both markers is determined. Little information is available about the location of internal landmarks during treatment, except when internal markers are periodically imaged using an invasive device such as an X-ray. However, the position or video image of the external markers on the chest and / or abdomen is determined with high accuracy and / or high speed. Similarly, the external sensor can supply the measurement data in real time, i.e. very fast. Thus, the position of the external landmark can be used in real time during treatment by inferring the position of the internal (accurate) marker with reference to the preoperative model of the relative position of the internal marker and the external marker. For confirmation, the position of the internal marker can be measured periodically during treatment. Devices that compensate for breathing and other movements of the patient in accordance with the present invention are described below.

FIG. 5 is a drawing showing a set of internal markers 152 of the invention placed on a target organ 151 within the patient's body 150. Moving target organs 151 include, for example, organs near the diaphragm, such as the lungs or liver, that move when the patient moves or inhales or exhales. It is desired by the present invention to track the movement of the target organ so that treatments such as ionized radiation are applied to the target organ and not to healthy surrounding tissues. To track the movement of the target organ 151, one or more internal markers 152 are attached at various locations on the target organ 151. In this case, as the target organ moves, the internal marker also moves as indicated by arrow 154. The position of the target organ can be accurately determined from the movement of the internal marker. In a preferred embodiment, one or more internal markers can be used to measure the movement of various regions of the target organ, and the internal markers can be made of gold. As a result, the internal markers cannot be seen from outside the body, but can be seen using imaging techniques (localization X-ray imaging is preferred, but ultrasound can also be used).

FIG. 6 is a drawing showing one or more internal markers 152 attached to a target organ 151 imaged by a stereotactic X-ray device. As shown in FIG. 6, the internal marker 152 on the target organ 151 is imaged by the first X source 160 and the second X source 162. Both X-ray sources 160 and 162 are arranged at a predetermined angle with each other, similar to the diagnostic X-ray beams shown in FIGS. 1 to 3. Both X-ray sources generate first and second diagnostic X-ray beams 164 and 166, and both diagnostic X-ray beams pass through the target organ 151 near the internal marker 152 and the first and second diagnostic X-ray receivers 168, respectively. , Received by 170. Both X-ray receivers 168 and 170 receive an X-ray beam and generate an electric signal corresponding to the X-ray. The stereotactic X-ray apparatus can determine the exact position of the internal marker 152 by analyzing the created image.

7A-7D show examples of X-ray images of the target organ containing the internal marker 152 according to the present invention. 7A and 7C are the same X-ray images, with the internal marker 152 unenhanced and computerized, respectively. Similarly, FIGS. 7B and 7D are the same X-ray images, with the internal markers unenhanced and computer-enhanced, respectively. Thus, stereotactic radiography can determine the exact position of the internal marker. The problem is that with the use of stereotactic X-ray equipment, the position of internal markers can only be determined at predetermined intervals during treatment. More specifically, the imaging interval of the internal markers is necessary to limit the patient's exposure to radiation, as the therapeutic beam is not urged during radiographic imaging. However, periodic determination of the exact location of the target organ is not sufficient to accurately compensate for the patient's respiration and other movements. Thus, as described with reference to FIG. 8, one or more external markers are placed on the patient's skin near the target organ according to the present invention. The current state of breathing can be measured by observing video images of chest and / or abdominal movements instead of external markers.

FIG. 8 is a drawing showing a target organ 151 within a patient's body 150 having an internal marker 152 combined with one or more external markers 180 attached to the patient's skin according to the present invention. One or more external markers 180 attached to the patient's skin allow measurement of abdominal or chest wall movement. In the patient's breathing example, an external marker tracks external movement as the patient inhales and exhales. The external marker 180 is automatically tracked by many optical methods such as infrared or visible light, and the position of the external marker is measured more than 60 times per second. The external marker can also be attached to a belt, flexible ring or vest that is worn around the patient's waist.

However, when only external markers are used to compensate for patient migration, the target organ may move small, whereas the external marker may move large (and vice versa). Cannot accurately reflect the internal movement of. External markers are not accurate enough to compensate for patient movement. Therefore, it is necessary to combine an internal marker and an external marker in order to accurately track the movement of the target organ. Thus, periodic radiographs of the internal markers are synchronized with continuous optical tracking of the external markers for accurate tracking of target organ movement. In order to synchronize the movement of the internal marker with the movement of the external marker, it is necessary to determine the relationship between the position of the internal marker and the position of the external marker that will occur at the beginning of the treatment process. This will be described below with reference to FIG.

If any movement of the target organ is detected, a treatment system such as radiosurgery described above compensates for the movement in a number of ways. For example, the treatment system can move a treatment device, such as a beam generator 20, to the patient (and vice versa). The treatment system can also move the molding or aiming device within the path of the treatment device. The treatment system also activates the treatment device only when the target organ is within the treatment pathway and shuts off the treatment device when the target organ is not within the treatment pathway. One benefit of the mobility compensator of the present invention is shown and described below.

9A-9D are drawings showing one benefit of the mobility compensator according to the present invention. In particular, FIG. 9A shows a volume 200 to be treated without the use of safety seams. More specifically, this portion 200 has no safety seams at all, so the exact location of the target area to be treated is known and therefore healthy tissue is not damaged. Part 200 requires a safety seam 202, as shown in FIG. 9B, when the target area cannot be accurately determined, such as the target organ that is moved by the patient's breathing and other movements. The problem with safety seams is that the required radiation increases very quickly with the diameter of the target. For example, in the case of a spherical target, the ratio of the target diameter to the required dose is cubic. FIG. 9C shows a safety seam 202 for use in a typical radiosurgical device. FIG. 9D shows the very small safety seam 202 possible with the mobility compensator and method according to the invention. By reducing the size of the safety seam by half, the dose volume can be reduced by 1/8. Especially in the case of various cancers with an unpleasant prognosis, the therapeutic effect is greatly improved by combining a general radiosurgery device and the movement compensator of the present invention. Next, the movement compensation method during treatment according to the present invention will be described.

FIG. 10 is a flowchart showing a method 210 for compensating for respiration and other movements of a patient undergoing treatment using a radiosurgical device or the like. The first few steps of this method are performed before the patient's actual treatment. More specifically, at stage 212, the surgeon attaches a set of internal markers in or near the target organ during a short surgical procedure, and then at stage 214, just before treatment, near the target organ. Attach a pair of external markers to the patient's chest or abdominal wall. Then, at step 216, just before starting treatment for the patient, the processor of the radiosurgery device correlates the position of the internal marker with the position of the external marker. The method of correlating the internal marker and the external marker will be described later with reference to FIG. Once the position of the internal marker and the position of the external marker are correlated, treatment of the patient is initiated. The next step of the invention takes place during the treatment of the patient.

First, the device determines whether the total elapsed time since the last time the internal marker was imaged is equal to a predetermined number of seconds. The predetermined number of seconds is preferably between 2 and 10 seconds, more preferably about 10 seconds. If the total elapsed time is equal to a predetermined number of seconds, at step 220, the treatment beam is de-energized and an internal marker is imaged, for example using stereotactic radiography. The total elapsed time is then reset to zero and the method of the invention returns to step 218. Thus, according to the present invention, the internal marker is imaged every predetermined number of seconds. Returning to step 218, if it is determined that the total elapsed time is not equal to a predetermined number of seconds, the external marker is optically tracked at step 224 and the therapeutic beam is urged at the same time at step 226. External markers are tracked so that position data is fed to the processor of the radiosurgery device at a frequency of 60 times per second. The processor then correlates the position of the external marker with the position of the internal marker to generate position data for any change in the position of the target organ. Thus, during periodic imaging of the internal marker, the position of the external marker is used to track the position of the target.

When any movement of the target organ is detected, the treatment system such as the radiosurgical device compensates for the movement in various ways. For example, the treatment system moves a treatment device, such as a beam generator 20, to the patient, or conversely, moves the patient to the treatment device. The treatment device also moves the molding device or aiming device into the path of the treatment device to change the characteristics of the treatment device. The treatment system also urges the treatment device only when the target organ is within the treatment route and shuts off the treatment device when the target organ is not within the treatment route. Next, a method of correlating the internal marker and the external marker according to the present invention will be described.

FIG. 11 is a flowchart showing a method 230 for correlating the position of the internal marker and the position of the external marker according to the present invention. Several steps of this method are performed during the preoperative process, while several steps are performed during the actual treatment. More specifically, in stage 232, a series of times for both internal and external markers throughout the entire respiratory cycle so that multiple points corresponding to internal and external markers are created during the preoperative phase. Create a series image. Each of the plurality of points corresponding to the external marker and the internal marker is called a point cloud. Next, in step 234, the processor of the radiosurgery device adapts one curve to the point created for the internal marker and another curve to the point created by the external marker. These curves can correlate the position of the outer marker with the position of the inner marker.

In step 236, during the actual treatment, the system creates the position x of the external marker at a particular point in time by a technique such as infrared imaging, which position x is adapted to the previously created curve of the position of the external marker. To. Next, in step 238, the position y of the point on the internal marker curve corresponding to the position x is determined by comparing both curves. This is a method known as the interpolation method. This method is performed for each marker. Using this method, the position of the external marker is correlated with the position of the internal marker, which allows the system to accurately determine the amount of movement of the target organ without actually imaging the internal organ. Another way to correlate the position of the internal marker with the position of the external marker is to use a neural network trained to perform the interpolation method, or after calculating the point cloud, the internal marker and the external marker. To use a known mathematical interpolation method that establishes a correspondence with.

Next, four different embodiments of the method of compensating for a patient's breathing and other movements according to the present invention will be described. In all these embodiments, respiratory and diaphragmatic migration is limited and minimized by tying or holding the abdomen. In the first embodiment, one or more small metal markers (also known as landmarks) are attached to the target organ prior to treatment. If possible, 3 or 4 metal markers with different shapes or sizes, such as small gold beads, can be used. The exact location of these internal markers is determined by two X-ray cameras that take a stereoscopic image of the target site. Also, one or more infrared probes can be attached to the patient's skin surface. Infrared probes perform very accurate and fast position readings, but only show the surface of the patient's body. In this embodiment, the internal imaging of the internal marker and the external imaging of the external marker (that is, X-ray imaging and infrared imaging) are combined. More specifically, prior to treatment, a series of images of both modes (ie, X-ray and infrared, respectively) are obtained. In these images, the time of image acquisition is recorded. That is, at least both styles of images are obtained at the same time, and therefore the image acquisition time point does not change for more than about 0.01 seconds. In this way, a series of preoperative images of external and internal landmarks are obtained, each image having a time stamp. These series of images determine a model of relative movement between the internal and external landmarks as described above.

During actual surgery, it is not possible to obtain more than one X-ray image every given number of seconds due to the inability to expose the patient to excessive radiation and the inability to activate the treatment beam when radiography is performed. Have difficulty. Therefore, X-ray imaging alone is too slow to follow respiratory movements with high accuracy. Therefore, external landmarks on the skin surface, such as those found in infrared systems, are used for intra-operative localization, where we use a previously calculated model of the relative movement of the internal and external markers. Refer to continuously. This makes it possible to predict the exact placement of internal landmarks (gold beads) when an X-ray image is not available. Next, a second embodiment of the method of the present invention will be described.

In the second embodiment of the method according to the invention, no internal landmarks attached to the target organ are used. Instead, an ultrasound camera is used in combination with an infrared tracking system to obtain a series of preoperative images. The infrared system of this embodiment establishes both the position of the external landmark and the position of the (movable) ultrasonic camera on which the operator must move during this preoperative phase. During the preoperative phase, ultrasound images are analyzed manually or semi-automatically to position the target. During treatment, the acquired migration model can determine the location of the internal target organ from the location of the external marker, so external landmarks (infrared probes) are used to compensate for the migration of the target organ. Next, a third embodiment of the method of the present invention will be described.

This third embodiment is very similar to the second embodiment, except that an air flow measuring device is used instead of the ultrasonic camera. An air flow measuring device can consist of a mouthpiece that records the direction and volume of air flow and correlates these measurements with the position of any other mechanism that detects the position of an internal reference point or internal organ. In this embodiment, a reference position of a target organ, such as the lungs, such as a complete exhalation state or a complete inspiratory state or any intermediate respiratory state is used to correlate the current respiratory state with the pre-measurement state. The movement and position of the target organ is determined during treatment, and the position of the treatment device is moved based on the determined movement of the target organ. Next, a fourth embodiment of the present invention will be described.

In the fourth embodiment of the present invention, a slightly different technique is used. More specifically, during most radiation treatments, the patient is awake and conscious, so whether the movement observed by real-time tracking of external markers is actually due to breathing or other small movements of the patient's body. Is often difficult to determine. Such other movements of the body are caused, for example, by sneezing or other sudden movements. A pair of X-ray cameras can be used in addition to the ultrasound cameras described above to detect and track these other movements. In this embodiment, the ultrasound camera is only used preoperatively to determine the correlation between target movement and movement of external landmarks as described above. Thus, a series of preoperative images are reacquired to determine the relationship between the patient's skin surface migration and the target organ. During treatment, a radiographic camera is used to determine a patient's sudden movement based on a well-known computer method for automatically finding bone-like landmarks in x-ray images. These x-ray images are compared with preoperative tomographic images (CT or MR images) to determine the patient's sudden movement.

Although the present invention has been described above with reference to the specific embodiment, those skilled in the art can make changes to the embodiment without departing from the principle and spirit of the present invention described in the claims. Will.