FR2641180A1 - Radiology system for angiographic examination and method for implementation - Google Patents

Abstract

The invention relates to radiology systems for angiographic examinations. The invention resides in the fact that the angiographic examination proper is preceded by a radioscopy (fluoroscopy) phase so as to determine and record various determined positions of the table 19 in a device 7, 21 for obtaining the best match between the morphology of the patient and the input diameter of the image collector. During the actual examination, the table resumes the same positions automatically under the control of the practitioner who follows the advance of the contrast product. The invention makes it possible to perform angiography by differential images in real time during examination and in review and treatment phase. The invention is applicable to angiography of the lower limbs.

Description

RADIOLOGY SYSTEM FOR EXAMINATION
ANGIOGRAPHIC AND METHOD OF IMPLEMENTATION
The invention relates to radiology systems and, more particularly, those which are used for angiographic examinations of the lower limbs. It also relates, in said systems, to the patient support tables, in particular their position control device so as to obtain determined positions of the patient relative to the X-ray source. Finally, it relates to an implementation method of the device and the radiology table so as to perform an angiographic examination.

Angiography is the radiological technique applied and adapted to the vascular network: arteries, veins, perfused tissues. It uses iodine-based liquids, called contrast, opaque to X-rays, and injected into the vascular network to allow its visualization by differentiation with the surrounding tissues. More specifically, the patient is lying on a table which is provided so as to move under an X-ray source associated with a receiver placed on the other side of the patient relative to the source. The practitioner injects the liquid opaque to X-rays, called a contrast agent, into an artery or vein of the patient lying on the table. Then, a few seconds after this injection, he takes several successive shots of the patient so as to visualize and measure the progress over time the contrast agent in the blood vessels.

When the angiographic examination is limited to a part of the body which corresponds to the field of the receiver, that is to say to the dimensions of the photographic film or of the luminance amplifier, the images are taken without moving the patient, it that is, the table, relative to the source receiver assembly (or vice versa).

When the angiographic examination concerns the lower limbs, that is to say a length of approximately 120 centimeters, several methods are currently implemented.

 The first consists in using as receiver equipment called arteriophiebographs comprising on a hexagonal drum six cassette / film pairs of 120 cm long x 35 cm wide and allowing six irradiations therefore six photographic shots at different times.

For each picture corresponding to a cassette / film pair, the entire surface of the lower limbs is irradiated. This process leads to significant exposure to X-rays, which can be detrimental to the patient, and at a relatively high cost due to the price of six large format photographic films.

 . A second method consists in examining the lower limbs area by area, each area corresponding for example to a useful field of 35 x 35 cm or to a diameter of 30 cm or 35 cm. For this, a first injection of contrast product is carried out and several successive shots of the area close to the injection are made. Then, the table is moved to examine the next area after having carried out a second injection of the contrast product and so on for the following areas. Such a process leads to several injections, which takes time, causes considerable discomfort to the patient and is expensive in terms of contrast product. In addition, it is not easy to monitor the progress of the contrast product so that the shots taken for areas other than the area near the injection allow the contrast medium to be seen. This progression is all the more difficult to follow as the speed of movement of the blood is variable from one individual to another and depends on the pathology of the patient.

 A third method consists in carrying out a single injection and in carrying out a sequential displacement of the table between each photograph or each series of photographs.

Currently, the radiology tables which are provided for this kind of examination have a selection of advances according to fixed steps and at constant time intervals or the duration of which is at the discretion of the practitioner. They do not allow the practitioner to easily master the phases of the examination so as to follow the progress of the contrast medium whatever the field of the receptor, the patient's morphology and the pathological aspects.

An object of the present invention is therefore to provide a radiology system for angiographic examination which allows the practitioner to follow with certainty the progress of the contrast product injected all at once in the blood vessels of a patient, in particular those of his legs.

Another object of the present invention is to provide, for such a radiology system, a device for controlling a patient support table which can be programmed by the practitioner as a function of a brief prior examination of the patient by radioscopy.

Another object of the present invention is a method for implementing the radiology system and the device for controlling the patient's support table so as to obtain an angiographic examination as perfect as possible in a minimum period of time. exposure to X-rays and at the lowest possible cost.

The invention relates to a radiology system for angiographic examination which comprises a stand supporting an X-ray source and an X-ray receiver cooperating with the source, a device for processing the signals detected by the receiver so as to obtain an image. for radiological visualization of the body of a patient on a screen of the television type, a radiology table comprising means for moving a patient support relative to the X-ray beam, characterized in that it further comprises a device for recording of a number N of determined positions of the support which are selected by the user of the system during a preliminary examination according to the characteristics of the patient to be examined and a device for remote control of the recording device so as to bring successively said support at said positions determined during the angiographic examination and to be carried out at each position at minus an image of the patient.

 The invention also provides for recording for each position of the patient support not only the coordinates of the position but also other information such as the parameters of the X-ray source.

In a variant, the system further comprises a device for differential processing of patient images for each position of the support, between a mask image obtained without contrast product and an image obtained with contrast product.

The invention also relates to a method of implementing the radiology system characterized in that it comprises the following operations a) the prior examination by radioscopy of the parts of the patient's body to correctly place the patient with regard to his morphology and area of interest as well as dimensions of the receiver, examination during which the recording takes place, of determined positions of the support / patient assembly according to the morphology of the patient and the size of input of the receiver , b) producing, after injection of a dose of contrast product, angiographic images at the positions of the support previously recorded.

Other characteristics and advantages of the present invention will appear on reading the following description of a particular embodiment, said description being made in relation to the appended drawings in which - Figure 1 is a perspective view of 'a
radiology facility for angiographic examination
according to the invention; - Figure 2 is a view of the front face of a
table position memory device
according to the invention, and - Figure 3 is a block diagram of a system of
radiology for angiographic examination according to
the invention.

The radiology installation for angiographic examination comprises a stand 10 of the isocentric movement type and a radiology table 11. The stand 10 conventionally comprises a platform 12 on which is pivotally articulated about a vertical axis a column 13 for supporting an L-shaped arm 14. The arm 14 pivots via one of the branches of the L around a horizontal axis and the end corresponding to the other branch of the L carries a hoop 15 which is intended to move in a sheath not shown. The arch 15 is a semi-circular arc, one end of which carries in particular a source 16 of X-rays and the other opposite end of which carries in particular a receiver 17 of X-rays.

The radiology table 11 includes a pedestal 18 on which rests a table 19 proper on which the patient can lie down. The pedestal 18 and the table 19 comprise various devices, not shown, which make it possible to move it along three orthogonal axes referenced by the arrows references x, y and z in FIG. 1. These different displacements are obtained by electric motors whose setting on and off are controlled in particular using a control device 20 located near the table
According to the invention, provision is made to associate with this radiology table 11 a control device 21 for storing a certain number N of positions of the table 19 along the x axis and a remote trigger device 22 of a memory module 7 (FIG. 3). The memory control device 21 is normally close to the table 11 while the trigger device 22 is located in an area protected from X-rays where the practitioner stands for the part of the examination carried out with high X-rays.

In the case where N = 6, the storage control device 21 can be in the form of a box containing the appropriate electronic circuits and the front face (FIG. 2) of which comprise various control buttons 23, 24 and 25 and various light displays 31 to 36. The light displays 31 to 36 serve to display the six positions of the table 19 during the recording phase and the actual angiographic examination sequence. Button 23 is used to control the recording of each position of the table during the recording phase. The button 24 is used to erase the recordings of the positions of the table 19 and the button 25 is used, on the one hand, to indicate the end of the recording phase and, on the other hand, to control at the same time the return of table 19 at an original position.

The triggering device 22 comprises a button for controlling the advance 26 of the table 19 according to the positions recorded during the recording phase and a button 27 for controlling the return of the table to its original position, in particular at the end of the actual examination sequence. This trigger device 22 is generally part of the control console of the entire installation, which console is located in a protected area.

Figure 3 gives the simplified block diagram of a radiology system for angiographic examination. This system comprises the elements described in relation to FIGS. 1 and 2, namely the stand 10, the source 16 of X-rays, the receiver 17, the table 19 mounted on the pedestal 18, the control desk 20, the control device of the memorization 21 and the triggering device 22.

In FIG. 3, the stand 10 is associated with an electronic control device 9 which is connected to a central electronic management unit 41 essentially consisting of a microprocessor. The source 16 is controlled by a power supply source 6 which is connected to the central member 41. The receiver 17 is connected to a display device 43 for the images received via a processing device 42. The pedestal 18 is associated with an electronic control device 8 for the movements of the table 19 which is connected to the central member 41. This control device 8 comprises in particular a storage module 7 for the N = 6 positions of the table 19.

The triggering device 22 is part, as indicated above, of a general control console 40 located in the protected area. This desk 40 allows the control of different organs of the radiology system.

This control is carried out through the central electronic management unit 41 which is connected to the stand 10 via the device 9, to the source 16 of X-rays via the power source 6, to the receiver 17 via the device 42, to the position control device 20, to the storage control device 21. These various connections are made by the intermediary of a bus shown diagrammatically by the square bearing the reference 48.

To implement the radiology system for angiographic examination, the invention proposes first carrying out a radioscopic phase which allows the patient's anatomy to be displayed on the screen 43 by moving the table using the device. 20. As the table 19 moves, the practitioner selects the positions of the table which will correspond to angiographic images during the following examination sequence, taking into account the patient's morphology, the size of the image receptor 17 and the overlap desired by the practitioner. This selection is made using the recording device 21 which then accurately records in the storage module 7 the various information relating to the selected positions.

 After returning from table 19 to the original position, that is to say the one from which the selected positions have been measured, the angiographic examination proper can begin by injecting the dose of contrast product. The practitioner then triggers the advancement of the table 19 from one position to the next using the trigger device 22.

This advance is made at the appropriate time as a function of the progression of the contrast product, according to the speed of the blood flow. The visualization of the progress of the product is done by means of the elements 17, 42, and 43 which are provided to obtain the persistence of the image. This persistence is conventionally obtained by keeping the last recorded image on the screen and updating it with each new exposure. At this advance is synchronized the emission of X-ray radiation so that each stop of the table at a determined position coincides at least with an emission of X-ray radiation. Thus, at each position of the table, at least an angiographic picture.

When the photograph at the last position has been taken, the practitioner obtains the return of the table to the original position by actuating the control device 22 of the desk 40.

The process which has just been described allows the practitioner to select without fail the patient positions which will make it possible to follow on the angiographic images the progress of the contrast product because the advancement of the table will have been programmed according to the characteristics of the patient. .

According to the invention, this method also allows the practitioner to modify the parameters of the X-ray at each photograph by programming them during the pre-examination phase, for example by recording them in a memory 44 of the member 41. During during the examination phase, these saved parameters are read in synchronism with the table positions.

The angiographic images which are obtained using the radiology system and the method described above obviously include the image of the bones of the skeleton, which sometimes makes visual detection of the contrast product difficult.

The system and the method of the invention make it possible to remedy this drawback because they are easily adapted to the production and processing of so-called subtracted differential images which make the repeating elements of two images of the same part of the body disappear. patient. To this end, the diagram of Figure 3 must be modified to add a differential image processing device 45, known elsewhere. In addition, screen 43 can be associated with a photographic camera 46 called a reprographer and / or a video recorder 47. These various elements 43, 45, 46 and 47 are connected together by a bus shown diagrammatically by the square bearing the reference 49.

The method described above must also be modified to include a phase of establishing the mask images for the different positions of the table which have been programmed during the fluoroscopy phase. These masks are recorded digitally in a memory of the device 45 during this intermediate phase during which the table is moved automatically and programmed without having injected a contrast product into the patient's blood vessels. During the examination phase with contrast agent, these masks are subtracted from the corresponding image with contrast agent and this results in the disappearance of the identical elements of the two images; only the contrast agent which was not in the mask therefore remains visible. The image which then appears on the screen 43 then shows only the vessels filled with contrast agent; the images are kept in memory 42 and can be recorded simultaneously on the magnetic support of the video recorder 47.

 It will be noted that this additional phase of establishing the masks does not need to be obtained by an automatic displacement of the table 19; it suffices to pass from one position to the next by a feed control manipulated by the practitioner, the important thing being to resume exactly the same positions of the table and the patient.

In the description of the invention which has just been made, provision has been made for recording the different positions of the table along the x-axis. Provision has also been made for recording the emission parameters of the source 16, parameters which are associated with each position of the table. This information can be supplemented by others such as the positions along the y axis and the z axis, the positions of the collimator associated with the X-ray source, the positions of the contour filters, etc.

Claims (7)

1. Radiology system for angiographic examination which comprises a stand (9,10) supporting a source (6,16) of X-ray and a receiver (17) of X-rays cooperating with the source 16, a processing device (42) images detected by the receiver (17) so as to obtain a radiological visualization image of the body of a patient on a screen (43), an X-ray table (11) comprising means for moving a patient support (19) relative to a pedestal (8,18), characterized in that it further comprises a device for recording (7,21) a number N of determined positions of the support (19) which are selected by the system user during a preliminary examination according to the characteristics of the patient to be examined and of the receiver and in that it comprises a remote control device (22 ) of the recording device so as to successively bring said support (19) to said positions determined during the angiographic examination and to produce at each position at least one image of the patient. 2. Radiology system according to claim 1, characterized in that it further comprises a central electronic management unit (41,44) which is provided for recording during the preliminary examination the parameters of the source (16) of X-rays for producing during the angiographic examination the image of the patient at each determined position of the support (19) in accordance with said parameters. 3. Radiology system according to claim 1 or 2, characterized in that it further comprises a differential processing device (42,45) of the images obtained and a recording device (46 or 47) of the differential images associated with the display screen (43), so as to first obtain images without contrast product of the parts of the patient's body corresponding to the determined positions of the support (19), said images or masks then being subtracted in the device (45 ) to the corresponding images of the same parts of the body obtained with the contrast product, the result of the subtractions being displayed on the screen 43. 4. Method for implementing the radiology system according to claim 1 or 2, characterized in that it comprises the following operations a) the prior examination by radioscopy of the parts of the  patient's body by moving the patient support  so as to correctly place the patient with regard  to its morphology and to the area of interest as well as  dimensions of the receiver, and during which takes place  recording of determined position # s of the support  (19) depending on the characteristics of the patient and  of the radiology device during the examination  prior, and b) carrying out, after injection of a dose of product  contrast, angiographic images at positions  previously recorded support, 5. Method according to claim 4, characterized in that the movement of the support (19) from one position to the next is controlled by the practitioner. 6. Method according to claim 4 or 5, characterized in that it further comprises an operation of recording the parameters of the source (16) of X-rays for each position of the support. 7. Method according to claim 4, 5 or 6, in its application to a radiology system according to claim 3, characterized in that it further comprises, before the production of angiographic images, a recording operation of mask images for the different determined positions of the support in the absence of a contrast product.