An X-ray diagnosis apparatus is configured to control at least one of the X-ray diaphragm which restricts the irradiation range of the X-ray and the compensation filter which attenuates the amount of the X-ray based on at least one of the rotation position or the position parallel to the body axis of the X-ray source.

FIELD OF THE INVENTION

The present invention relates to an X-ray diagnosis apparatus and a method for creating an X-ray image.

BACKGROUND OF THE INVENTION

A conventional X-ray diagnosis apparatus irradiates an X-ray from an X-ray tube to a patient, and detects the X-ray penetrated through the patient with an image intensifier (hereinafter referred to as I.I.), which changes the X-ray into a light and an imaging tube or a charge coupled device changes the light into an electronic signal or a flat panel detector (hereinafter called as a FPD) directly changes the X-ray into the electronic signal. Thus, an X-ray fluoroscopic image is obtained. The X-ray apparatus enables an operator to observe flow and movement of a contrast agent inside the patient on a display. Moreover, the fluoroscopic image is stored in a memory and used for various image processes, such as enlargement/contrast adjustment/space filter processes or minimum/maximum trace processes or subtraction process or adding process for removing a noise, and the like.

The subtraction process for obtaining a subtraction image of a part of the patient using the X-ray diagnosis apparatus is explained below. In order to perform the subtraction process, the fluoroscopic image, a mask image, and a contrast image are obtained. The fluoroscopic image is used for setting a position of an X-ray diaphragm and a compensation filter. The mask image and the contrast image are basic images to create the subtraction image. Hereinafter, an imaging for obtaining the fluoroscopic image is called a fluoroscopic imaging, and an imaging for obtaining a mask image and a contrast image is called a main imaging. In the fluoroscopic imaging, the operator sets X-ray fluoroscopic terms (X-ray tube voltage, X-ray tube current, fluoroscopic time, etc.), considering patient information, such as a patient age, sex, the portion of the body being imaged and other factors (such as, but not limited to, patient condition, pregnancy status, medical conditions, allergy to the contrast agent, specific needed nursing care). The X-ray is irradiated to the patient based on the fluoroscopic factors, and the fluoroscopic image is displayed on the display. The operator adjusts a position of a supporting unit for supporting the X-ray tube and the I.I., in order to position an imaging area at an appropriate part of the patient. The operator sets positions of the X-ray diaphragm and the compensation filter, observing the fluoroscopic image.

The main imaging starts after the X-ray diaphragm and the compensation filter are set. In the main imaging, the mask image and the contrast image are obtained in order. The mask image is aligned to the contrast image, and the subtraction process between these images is performed. The subtraction image is displayed on the display in a real time.

In the conventional X-ray diagnosis apparatus, the X-ray diaphragm and the compensation filter are fixed at such a position that the imaging area is adequate during the main imaging, such as during a bolus chase imaging where the X-ray and the I.I. automatically move. That is, wherever the X-ray tube and the I.I. move within the imaging area, the X-ray irradiated to the patient is not blocked or attenuated. However, since the X-ray diaphragm is fixed during the main imaging, the irradiation range of the X-ray is wide, the amount of the X-ray irradiated to the patient increases, and the influence of scattered X-ray appears. Moreover, since the compensation filter is fixed during the main imaging, X-ray halation partially remains. However, it is difficult to manually adjust the position of the X-ray diaphragm or the compensation filter according to a contour of the patient during the main imaging where the X-ray tube and the I.I. automatically move.

SUMMARY OF THE INVENTION

The present invention intends to solve the above-mentioned problems. One aspect of the present invention is an X-ray diagnosis apparatus including an X-ray source configured to irradiate an X-ray to an object, a diaphragm configured to restrict an irradiation range of the X-ray, a detector configured to detect the X-ray penetrated through the object, a bed configured to support the object, a mechanism configured to move a position of the X-ray source in a direction taken along the bed, and a controller configured to control the diaphragm based on the position of the X-ray source in the direction.

Another aspect of the present invention is an X-ray diagnosis apparatus including an X-ray source configured to irradiate an X-ray to an object, a diaphragm configured to restrict irradiation range of the X-ray, a detector configured to detect the X-ray penetrated through the object, a bed configured to support the object, a mechanism configured to rotate a position of the X-ray source around the bed, and a controller configured to control the diaphragm based on the position of the X-ray source.

Another aspect of the present invention is an X-ray diagnosis apparatus including an X-ray source configured to irradiate an X-ray to an object, a compensation filter configured to attenuate an amount of the X-ray, a detector configured to detect the X-ray penetrated through the object, a bed configured to support the object, a mechanism configured to move a position of the X-ray source in a direction taken along the bed, and a controller configured to control the compensation filter based on the position of the X-ray source in the direction.

Another aspect of the present invention is an X-ray diagnosis apparatus including an X-ray source configured to irradiate an X-ray to an object, a compensation filter configured to attenuate an amount of the X-ray, a detector configured to detect the X-ray penetrated through the object, a bed configured to support the object, a mechanism configured to rotate a position of the X-ray source around the bed, and a controller configured to control the compensation filter based on the position of the X-ray.

Another aspect of the present invention is an X-ray diagnosis apparatus including an X-ray source configured to irradiate an X-ray to an object, a compensation filter configured to attenuate an amount of the X-ray, a detector configured to detect the X-ray penetrated through the object, a bed configured to support the object, a mechanism configured to move a position of the X-ray source to parallel to the bed, and a controller configured to control the compensation filter to move in an opposite direction to a direction of movement of the X-ray source at the same speed as the movement of the X-ray source such that the compensation filter relatively stops to the bed.

Another aspect of the present invention is a method for obtaining an X-ray image including irradiating an X-ray to an object, restricting an irradiation range of the X-ray, detecting the X-ray penetrated through the object, moving a position of the X-ray source in a direction taken along the bed, and controlling the diaphragm based on the position of the X-ray source in the direction.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the present invention is explained referring to the figures.FIG. 1is a block diagram of an X-ray diagnosis apparatus. The X direction is approximately parallel to a width direction of a patient, the Y direction is approximately parallel to a body axis of the patient, and the Z direction is approximately parallel to a thickness direction of the patient. As shown inFIG. 1, an X-ray diagnosis apparatus includes a supporting unit16and a main control unit12. The supporting unit16includes a C-arm and a bed17. An X-ray tube11that irradiates an X-ray is mounted on one side of the C arm, and an X-ray diaphragm unit13that blocks the X-ray irradiated to an unnecessary area is provided on a patient P side of the X-ray tube11. A compensation filter unit15that attenuates the X-ray to restrain halation is also provided on the patient P side of the X-ray tube11. On the opposite side of the C-arm to the bed17, an X-ray grid4, which cuts a scattering X-ray penetrated through the patient P; an I.I.19, which changes the remaining X-ray to an optical image; an optical unit21, which corrects a size of the optical image; and a TV camera (or CCD, for example)23, which changes the optical image to a TV image signal, are mounted.

The main control unit12includes a system control unit25; an X-ray control unit29, which controls a high voltage generating unit31to generate high voltage impressed to the X-ray tube11; an X-ray diaphragm control unit33, which controls the degree (X, Y direction) of opening between X-ray diaphragms; and a compensation filter control unit35, which controls a position (X direction); a rotation angle φ, and a type of a compensation filter in the compensation filter unit15. Moreover, the main control unit12includes a supporting control unit37that controls a position (Y direction) of the C-arm to the bed17, an I.I. control unit39that controls the I.I.19, a camera control unit41that controls the TV camera23, an image memory44that stores an X-ray image obtained by the TV camera23. Furthermore, the main control unit12includes a display unit43that displays the X-ray image obtained by the TV camera23, a diaphragm, and compensation filter memory14that stores a position, etc. of the X-ray diaphragm and the compensation filter, a virtual diaphragm/compensation filter creation unit18, which creates a graphic image of the X-ray diaphragm and the compensation filter on the display unit43, and an operation unit27(for example, a keyboard and a mouse, or the like), which allows an operator to input instructions.

The X-ray diaphragm unit13is explained in detail, referring toFIG. 2, which is a top view of the X-ray diaphragm unit13from the X-ray tube11. The X-ray diaphragm unit13has a plurality of X-ray diaphragms45,47,49, and51. These diaphragms may be made of lead, for example, which limits the X-ray. The X-ray diaphragm45and49symmetrically move, and the X-ray diaphragms47and51symmetrically move. InFIG. 2, the X-ray diaphragms47and51are arranged at a back side and the X-ray diaphragms45and49are arranged at a near side. An area (indicated as dotted lines) surrounded by the X-ray diaphragms shows an area where the X-ray irradiated from the X-ray tube11passes, and the X-ray diaphragms45,47,49, and51symmetrically and asymmetrically move to extend or narrow the pass area. Thus, the irradiation area of the X-ray to the patient P may be controlled.

With reference toFIGS. 3A and 3B, the compensation filter unit15is explained in detail. The non-limiting illustration ofFIG. 3Ashows a sectional view of the compensation filter unit15from the body axis of the patient P, andFIG. 3Bshows a top view from the X-ray tube11. The compensation filter unit15includes a plurality of types of the compensation filters15a,15b, and15c, which are arranged along the direction of the X-ray irradiation (indicated as dotted lines). The compensation filter15cis far from the X-ray tube11, and the compensation filter15ais near the X-ray tube11. Generally, each compensation filter is made of, for example, acrylic or the like. Forms of the compensation filters15athrough15cmay be different from each other.

For example, the compensation filter15bmay have an elliptical form and the compensation filter15cmay have a rectangular form. In the non-limiting illustration ofFIG. 3B, the compensation filter15ais illustrated in the shape of a trapezium. These compensation filters15a,15b, and15cmove in the X and Y directions and rotates on a X-Y plate (the rotation angle is shown as φ). One or more of the compensation filters move to interrupt and attenuate the X-ray. InFIG. 3A, the case where the compensation filter15ainterrupts the X-ray is shown.

Next, an operation of the X-ray diagnosis apparatus is explained in the order of the fluoroscopic imaging, a setup of the X-ray diaphragm/compensation filter, and the main imaging.

The fluoroscopic imaging and the setup of the X-ray diaphragm/compensation filter is explained with reference to the non-limiting illustration ofFIG. 4, which is a flow chart. In the first embodiment, so-called bolus chase imaging is explained as one example. The bolus chase imaging is that the C-arm slides along a longitudinal direction of the bed17without rotation, and a contrast agent injected into the patient P is imaged. In Step61ofFIG. 4showing the fluoroscopic imaging, the operator (generally a doctor or a radiological technician) checks information (such as a patient name or other relevant information) about the patient P, the operator inputs suitable X-ray fluoroscopic terms (such as X-ray tube voltage, X-ray tube current, fluoroscopic time, or other appropriate parameters) for the patient P via the operation unit27, and the operator puts the patient P on the bed17.

In general, the X-ray tube current in the fluoroscopic imaging is lower than that of the main imaging, and is set up to an appropriate value by auto brightness control (ABC). The system control unit25controls the X-ray tube11to irradiate the X-ray to the patient P on the bed17via the X-ray control unit29and the high voltage generating unit31. At that time, the X-ray diaphragm control unit33controls the X-ray diaphragms45,47,49, and51of the X-ray diaphragm unit13so that the pass area of the X-ray is the maximum. Similarly, the compensation filters15athrough15cof the compensation filter unit15are held at positions such that the X-ray is not attenuated.

The X-ray penetrates through the patient P, and the scattered X-ray is cut by the X-ray grid4. The remaining X-ray is irradiated to the I.I.19. In the I.I.19, the optical signal corresponding to the amount of the incident X-ray is generated, and after the optical signal is corrected by the optical unit21, the corrected optical signal is changed to the electric signal as the TV image signal by the TV camera23. The TV image signal is changed to a digital signal by an A/D converter and the image processing performs on the digital signal. The processed digital signal is converted to a TV image signal to be displayed on the display unit43as the X-ray fluoroscopic image. Observing the X-ray fluoroscopic image on the display unit43, the operator may move the C-arm from (for example) an abdomen to a lower leg of the patient P by the operation unit27and the supporting control unit37. At that time, the X-ray continues to irradiate the X-ray to the patient P, and the fluoroscopic image from the abdomen to the lower leg of the patient P is displayed on the display unit43in a real time. The X-ray fluoroscopic image is stored in the image memory44. A similar operation is performed in the main imaging.

Setup (Step62through Step65inFIG. 4) of the X-ray diaphragm unit/compensation filter are explained. When the setup is performed, the X-ray is not irradiated from the X-ray tube11. In Step62for replaying the fluoroscopic image, the fluoroscopic image data is read out from the image memory unit44to be displayed on the display unit43.

FIG. 5shows an example displayed on the display unit43. The fluoroscopic image replays in a center of a monitor as a circular image. In Step63, the virtual X-ray diaphragm and virtual compensation filter are created on the fluoroscopic image72by the virtual diaphragm/compensation filter creation unit18. The virtual X-ray diaphragm is a graphic displayed on the display unit43, and one example is indicated by dotted lines74inFIG. 5. The virtual compensation filter is a graphic displayed on the display unit43similarly, and one example is indicated by dotted lines73inFIG. 5. A scale of the virtual X-ray diaphragm and virtual compensation filter correspond to a scale of the X-ray fluoroscopic image. When the X-ray fluoroscopic image is enlarged, the virtual X-ray diaphragm and virtual compensation filter are similarly enlarged. In Step64, the operator sets X and Y positions of the X-ray diaphragms.

In detail, the operator adjusts a size of the virtual X-ray diaphragm74on the monitor, by the operation unit27. According to the size of the adjusted virtual X-ray diaphragm74, X and Y position data of the X-ray diaphragms is calculated, and the position data is stored in the diaphragm and compensation filter memory14with the position data of the supporting unit16. In Step65, a position, an angle, and a sort of the compensation filter is set up. In detail, the operator selects one virtual compensation filter among candidates shown as icons71on the monitor.

The case where a virtual compensation filter in the center of the candidates is selected is explained below. The selected virtual compensation filter is displayed near the fluoroscopic image72on the monitor. The operator adjusts the X position of the virtual compensation filter73and also adjusts the angle of the virtual compensation filter73. The type, position, and angle of the virtual compensation filter is stored in the diaphragm and compensation filter memory14with the position data of the supporting unit16. Similarly, the operation unit27is used for selecting or adjusting the type, position, and angle of the virtual compensation filter.

After the setup is completed, the operator sets the X-ray diaphragm and compensation filter on another replayed fluoroscopic image of a different position. The operator sets the X-ray diaphragm and compensation filter on a whole imaging area (or only on a desired area). Thus, the X-ray diaphragm and compensation filter may be set, and a table of data (as shown, for example, inFIG. 6) is stored in the diaphragm and compensation filter memory14. The Y position of the supporting unit may be a position of the X-ray tube11which may be an absolute position which is not related to the bed17or a relative position to the bed17. The Y position of the X-ray tube may be a position of the I.I. or the C-arm, etc.

An operation of the main imaging is explained below. As described above, the main imaging is performed to obtain the mask image and the contrast image used for the subtraction process. The imaging for obtaining the mask image starts based on the instruction of the operator and is performed before the contrast agent is injected into the patient P. The X-ray tube11and the I.I.19automatically move from the abdomen to the lower leg or from the lower leg to the abdomen. After the mask image is obtained, the imaging for obtaining the contrast image starts. The imaging starts immediately after the contrast agent is injected into the patient P, based on the instruction of the operator. In the imaging for obtaining the contrast image, the X-ray tube11and the I.I.19move along the flow of the contrast agent at an arbitrary speed based on the instruction of the operator. The mask image is aligned to the contrast image and the subtraction process is performed. A trace of the contrast agent, namely a blood vessel, may be emphasized.

Differences between the mask image and the contrast image include the following points, for example. The mask image is obtained before the contrast agent is injected to the patient P, while the contrast image is obtained after the contrast agent is injected to the patient P. The imaging for obtaining the mask image is automatically performed, while the imaging for obtaining the contrast image is performed at arbitrary speed to chase the flow of the contrast agent, and other operations are similar to each other. Additionally, the direction of the imaging for obtaining the mask image may be opposite to or the same as the direction of the imaging for obtaining the contrast image. The imaging for obtaining the contrast image is explained below. An explanation of a similar operation for fluoroscopic imaging is omitted.

FIG. 7shows a flowchart of operation for obtaining the contrast image. In Step81, the Y position of the supporting unit16is detected by the system control unit25. In Step82, the X and Y position of the X-ray diaphragm is searched in the system control unit25. In detail, the first and second nearest data to the detected Y position is searched from the table shown inFIG. 6, and the X-ray diaphragm data corresponding to the first and second nearest data is specified.

In Step83, the position, angle and sort of the compensation filter are searched in the system control unit25. In detail, the data of the compensation filter within a field of view of the I.I.19is specified based the detected Y position of the supporting unit16and a field of view data of the I.I.19, which is pre-stored. In Step84, the X-ray diaphragm and the compensation filter are controlled based on the specified data.

The control of the X-ray diaphragm is explained with reference toFIGS. 8A and 8B. The controls of the X-ray diaphragm and the compensation filter may be independently performed simultaneously.FIG. 8Ashows the fluoroscopic image from the abdomen to the lower leg. In this case, four virtual X-ray diaphragms are set on the fluoroscopic image by the operator. If the detected position of the supporting unit16is the position near the abdomen inFIG. 8A, the data74aand74bare searched as the X-ray diaphragm data in Step82. In detail, as shown by solid lines ofFIG. 8B, the actual X-ray diaphragms45,47,49, and51are controlled as the virtual X-ray diaphragms74aand74b, and are connected smoothly. The portions shown as the dotted lines ofFIG. 8Bindicate the virtual X-ray diaphragms74shown as the solid lines ofFIG. 8A.

Since the X-ray diaphragm may be controlled as described above, the desired imaging area set by the operator receives adequate X-rays, while the X-ray is appropriately blocked from extraneous areas. In the above explanation, the four virtual X-ray diaphragms are overlapped from the abdomen to the lower leg as shown inFIG. 8A; however, the virtual X-ray diaphragm may be partially set. Where the virtual X-ray diaphragm is not set, the pass area of the X-ray between the X-ray diaphragms may be set as the maximum. That is, the X-ray diaphragm may not block the X-ray, if the virtual X-ray diaphragm is not set as well as the fluoroscopic imaging.

The control of the compensation filter is explained with reference toFIG. 9, which shows the fluoroscopic image from the abdomen to the lower leg. The non-limiting example where three virtual compensation filters73are set on the fluoroscopic image by the operator is shown inFIG. 9. The specified data of the compensation filter in Step83is used for controlling the compensation filter as the virtual compensation filter73is set. When the X-ray tube11moves to the lower leg from the abdomen, the compensation filter moves from the lower leg to the abdomen at the approximately same speed as the X-ray tube11. The movement of the compensation filter may continue until the compensation filter is beyond the field of view of the I.I19. Thus, since the compensation filter is controlled to move in an opposite direction to movement direction of the X-ray tube11at the approximately same speed, the attenuation of the X-ray is minimized.

After the main imaging, the operator performs an operative treatment on an affected area of the patient P, such as a closed blood vessel, after the operator confirms the affected area on the subtraction image obtained by the main imaging. In detail, while the X-ray is irradiated to the patient and the I.I. detects the X-ray to create the fluoroscopic image again, the operator inserts a catheter into the patient P. During the insertion of the catheter, the operator confirms a position of the catheter on the X-ray fluoroscopic image.

After the operative treatment is completed, the main imaging is preformed on the affected area again. In the main imaging after the operative treatment, the X-ray diaphragm and the compensation filter data used in the main imaging before the operative treatment may be used again. Thus, the operator performs the main imaging after the operative treatment to confirm a result of the operative treatment. The operative treatment may be performed immediately after the operative treatment or may be performed a few days after the operative treatment, for example.

In the first embodiment, since at least one of the X-ray diaphragm and the compensation filter is controlled on the fluoroscopic image according to the position of the X-ray tube, the X-ray diagram or the compensation filter can be set at an appropriate position. In addition, since the virtual X-ray diagram or the virtual compensation filter is used, the X-ray irradiation to the patient may be stopped during setting the X-ray diagram or the compensation, and the amount of the X-ray irradiated to the patient can be reduced.

The present invention is not limited to the above embodiments, and various modifications may be made without departing from the spirit or scope of the general inventive concept. For example, although the X-ray tube and the I.I. move to the bed which is fixed in the first embodiment, the bed may move during the fluoroscopic or main imaging. However, it is more desirable to move the X-ray tube and the I.I. than to move the bed, since the contrast agent may move unusually as a result of the movement of the bed. Moreover, although the X-ray diaphragm can be set in both of the X direction which is perpendicular to the body axis of the patient and the Y direction which is parallel to the body axis of the patient in the first embodiment, the X-ray diaphragm may be set in at least one direction. For example, the X-ray diaphragm data may be stored in only the Y direction of the X-ray diaphragm. Furthermore, although the X-ray diaphragm and the compensation filter are controlled according to the position in the body axis direction (Y direction) of the C-arm in the first embodiment, the C-arm may be fixed in the Y direction and may rotate instead. The X-ray diaphragm and the compensation filter may be controlled according to an angle of the rotation of the C-arm. Thus, a 3-dimensional subtraction process (so-called a rotation DSA) may be applied.

Although the virtual X-ray diaphragm and the virtual compensation filter are set on the replayed fluoroscopic image to set the X-ray diaphragm and the compensation filter in the first embodiment, the X-ray diaphragm and the compensation filter may also be set on the fluoroscopic image displayed in a real time while the X-ray is irradiated to the patient.

As described above, since at least one of the X-ray diaphragm and the compensation filter is controlled according to the position of the X-ray tube, the X-ray diaphragm or the compensation filter can be set at an appropriate position. Therefore, the amount of the X-ray irradiated to the patient is reduced or a halation on the X-ray image may be restrained.