Medical imaging equipment

A medical imaging equipment is described, including a radiation source for emitting measuring radiation, a receiver for receiving the measuring radiation, and a measuring region in which an object to be measured is placed, and which is situated in the beam path of the measuring radiation The receiver comprises a support which can be pivoted about a rotational axis and is adapted to mount at least two receiving devices. The receiving surfaces may be disposed alternately into a measuring position. A surface of the receiving device is parallel to the rotational axis of the support, and the rotational axis of the support is substantially perpendicular to the beam path of the measuring radiation.

RELATED APPLICATIONS

The present patent document is a continuation of PCT Application Serial No. PCT/EP2005/0533312, filed Jul. 11, 2005, designating the United States, which claims priority to German patent application No. 10 2004 034 239.3, filed on Jul. 15, 2004, both of is the applications hereby incorporated by reference.

TECHNICAL FIELD

The present application relates to medical imaging equipment for obtaining mammographic images, and in particular to imaging on several recording media.

BACKGROUND

Mammography is an x-ray examination of the female breast carried out using medical imaging equipment to obtain mammographic images. Such devices generally have a radiation source for x-rays. The female breast that is to be examined is x-rayed and a radiographic (fluoroscopic) image is obtained on an x-ray film arranged in the beam path below the female breast. During the examination, the female breast is normally held between a compression plate and an object table.

The use of x-ray films has the advantage that it represents a solution that is technically relatively sophisticated and at least in its purchase price relatively inexpensive and at the same time allows the radiographic image obtained by the x-ray film to be archived permanently.

A further advantage of using x-ray films is that x-ray films have a very large receiving surface, typically 18×24 cm or 24×30 cm, and a relatively high spatial resolution of about 14 Lp/mm (Lp=line pairs), which allows a high-definition full x-ray photo of the female breast to be made in a single measurement.

Instead of the x-ray film, which can only be used once, the use of a charge-coupled-device (CCD) sensor is known. The CCD sensors can be used in mammography equipment in the place of the x-ray film.

CCD sensors are electronic components which are suitable for spatial resolution measurement of radiation, in particular, of x-rays and, as a rule, are a matrix of radiation-sensitive cells, also known as pixels. To ensure easy adaptation to existing equipment, the CCD sensor is frequently integrated into a holder in the form of a conventional x-ray film cassette. The advantage of using CCD sensors is that currently available CCD sensors have a resolution of between 10 and 20 Lp per millimeter, which exceeds the resolution of x-ray films and the images are made available immediately and can be processed digitally. Thus, CCD sensors (unlike x-ray films) are suitable for obtaining real-time images (for example, of a biopsy).

The disadvantage of using CCD sensors is that, at present, CCD sensors with the required high resolution have a receiving surface which is markedly smaller than the receiving surface of x-ray films. Therefore, high resolution CCD sensors are currently only suitable for detailed x-ray photos of the female breast.

In addition, within the scope of FFDM (Full-Field Digital Mammography) the use of low resolution digital detectors is known.

The digital detectors used for FFDM currently have a typical resolution of 5 to 10 Lp per millimeter and, hence, a lower resolution than x-ray films. However, it is possible to realize receiving surfaces whose size is similar to the size of the receiving surfaces of conventional x-ray films. Therefore, using FFDM detectors, it is possible to produce a complete image of the female breast in one recording.

Thus, an advantage of the FFDM detectors is that the images are available in real time, the images can be digitally processed, and the receiving surfaces are relatively large. The current disadvantage is the relatively low resolution.

In an alternative to FFDM detectors, the use of digital luminescence radiography with storage screen technology to obtain mammographic images is also known. The resolution that can be achieved using this technology is currently about 8 Lp/mm.

In order to be able to combine the advantages, for example, of an FFDM detector with the advantage of an x-ray film, medical imaging equipment for obtaining mammographic images is known, which equipment has two receiving surfaces for x-rays.

A related art device with two receiving surfaces is shown inFIG. 6. The medical imaging equipment61for obtaining mammographic images has a head62with a radiation source63for emitting x-rays64and a receiving device65.

Both the head62and the receiving device are supported by a support column66, which is, attached to a floor stand or to the ceiling of a room.

In the device shown inFIG. 6, the receiving device65has a first receiving surface71in the form of a holder for x-ray films and a second receiving surface72in the form of a large-area low-resolution detector for FFDM recordings.

The two receiving surfaces71and72are arranged at right angles to each other and are supported by a support65of the receiving device via a mounting68attached to the support column66. The two receiving surfaces71and72can be pivoted around a rotational axis70alternately into a measuring position by turning the support manually. The rotational axis makes an angle of essentially 45° to the beam path of the x-rays64emitted by the radiation source63.

The 45° angle between the rotational axis70and the beam path of the x-rays64, together with the receiving surfaces71,72, which are arranged at an angle of 90° with respect to each other, ensures that after the support65has been pivoted about the rotational axis70, one of the receiving surfaces71is disposed outside the beam path parallel to the beam path and the other receiving surface72is disposed inside the beam path at right angles to the beam path of the x-rays64.

Provision is made for a measuring region, which is situated in the beam path between a respective receiving surface71or72in the measuring position and the radiation source64, the measuring region being provided to arrange an object67for measurement.

In addition, a compression plate75which is transparent to the measuring radiation is provided in the beam path above the object for measurement67.

The compression plate75is supported by a compression device74. A vertical movement of the compression plate75effected by the compression device74enables the object for measurement67to be compressed between the compression plate75and a supporting surface formed by the respective receiving surface71or72.

The previously known equipment has a disadvantage that it has a high space requirement73because of the wide pivoting movement about the axis70of the receiving surfaces71and72held by the support65.

In addition, the manufacture of a correspondingly pivotable mechanical connection with the respective receiving surfaces71,72having the precision required in the medical sector is technically very complex, and hence expensive.

SUMMARY

Medical imaging equipment is described comprising a radiation source for emitting measuring radiation, a receiving device for receiving the measuring radiation, and a measuring region, in which an object for measurement is placed and which is situated in the beam path of the measuring radiation between the radiation source and the receiving device. The receiving device has a support which may be pivoted about a rotational axis, the support supporting at least two receiving devices for the measuring the radiation and moves the receiving devices alternately into a measuring position. The receiving devices are arranged parallel to the rotational axis of the support, and the rotational axis of the support is approximately at right angles to the beam path of the measuring radiation.

The receiving devices are disposed substantially parallel to the rotational axis of the support, and the rotational axis of the support is substantially at right angles to the beam path of the measuring radiation. Rotating the support results in a movement that, in a horizontal direction, does not take up any more space than the support surfaces when the support is in the measuring position. The support may be designed as a shared housing for the receiving devices. Thus, the equipment has a space-efficient construction. In addition, it is possible to provide a particularly simple and robust mechanical connection of the support to the equipment.

The rotational axis of the support and the beam path of the measuring radiation make an angle of between 80° and 100°, particularly between 85° and 95°, preferably between 88° and 92° and more preferably of 90°.

The rotational axis may be arranged between the receiving surfaces and the receiving devices may be disposed so that each is approximately bisected by a perpendicular projection of the rotational axis.

After the support has been turned, the respective receiving device comes to rest in the respective measuring position centric to the rotational axis. This allows the equipment to be operated intuitively and, therefore, easily. In addition, in this way, errors caused by an erroneous estimation of the spatial position of the receiving surface may be avoided. In addition, when being pivoted, the protrusion of the support is reduced.

Generally, the rotational axis is arranged centrally in the beam path of the measuring radiation and may be situated in the geometric center of a volume enclosed by the support for the receiving devices.

In an aspect where the rotational axis is in the geometric center of a volume enclosed by the support, the support has a small orbit when it pivots. Further, a user can intuitively predict the course of a pivoting movement about the rotational axis.

The support may also have a surface for placing the object for measurement. The upper surface of the support can be used as the lower compression surface for the compression of the female breast while a mammography recording is being carried out. This reduces the number of components required and, hence, the cost of the equipment.

A control device may be situated between the receiving devices and carried by the support, for controlling the received measuring radiation. By using a control device carried by the support for controlling the received measuring radiation, it is possible to use a shared control device for different receiving devices, which reduces the number of components required. The control device can, for example, be used for an automatic exposure speed control.

The support may carry a shield, which is arranged in the beam path of the measuring radiation and disposed between the radiation source and the receiving devices, which are not in the measuring position.

By shielding the receiving devices not in the measuring position, it is possible to prevent x-rays from emerging from a side of the support away from the radiation source so that parts of the patient's body that are not the subject of the examination from being radiated. In this way the patient's exposure to radiation can be reduced. Moreover, the shield may also prevent unintentional exposure of the receiving surface that is not situated in the measuring position and also may prevent this receiving surface being exposed to radiation.

In an aspect, the support carries two essentially parallel receiving devices for the measuring radiation. A construction of this type can be realized using a compact design.

In another aspect, the support carries three receiving devices for the measuring radiation, wherein adjacent receiving devices together are disposed at an angle of essentially 60° with respect to each other. This allows three receiving surfaces to be realized in one compact design.

In yet another aspect, the support carries four receiving devices for the measuring radiation, wherein adjacent receiving surfaces together are disposed at an angle of essentially 90° with respect to each other. This construction allows the use of four receiving surfaces while at the same time retaining a compact design.

The measuring radiation emitted by the radiation source is an x-ray beam. One of the receiving devices is a solid state detector for x-rays, and another of the receiving devices is an x-ray film. One of the receiving devices may be a luminescence radiography screen. Screens of this kind are also known as “storage screens”.

DETAILED DESCRIPTION

In the following, the examples are described in detail with reference to the attached drawings. In the drawings, identical reference signs mark identical components or components with the same functions in the various views,

FIG. 1Ashows a side view andFIG. 1Ba front view of the equipment. The medical imaging device1has a radiation source3for emitting x-rays4, carried by a head2. The head2is carried by a support column6. Underneath the radiation source3, there are receiving devices for receiving the x-rays4emitted by the radiation source3.

The receiving devices are carried by the support column6and may include a motor8, a first bracket9carried by motor8and a support5carried by the first bracket9. The support5, which may be made out of a carbon fiber material, is situated in the beam path of the measuring radiation4.

Alternatively, the support5can be made from a different material, such as, for example, plastic. Such materials are selected to be substantially transparent to the measuring radiation.

A measuring region for arranging an object for measurement7is provided between the support5and the radiation source3, in the radiation path of the x-rays4, and the object for measurement may be a female breast.

As can be seen from theFIGS. 1A and 1B, an upper surface of the support5turned towards the radiation source3, is also used as a contact surface for the respective object for measurement (here, the female breast7).

A compression plate22which is substantially transparent to the respective measuring radiation is provided in the beam path of the x-rays4above the object for measurement7. The compression plate22may be made from a plastic material or materials as used for the support5.

The compression plate22is carried by a compression device21, which is attached to the support column6of the medical imaging device1. The compression plate22may be moved vertically by the compression device21, and the object for measurement7may be compressed between the compression plate22and the contact surface formed by the support5. The surface of the support5may thus also used as the lower compression surface. For improved clarity of presentation, the compression plate22and the compression device21are not shown inFIG. 1B.

The support5may be pivoted about a rotational axis10by the motor8via the first bracket9. Thereby, the rotational axis10is disposed at an angle α of approximately 90° to the beam path of the x-rays4. The angle α may be between 80° and 100°, particularly between 85° and 95° and preferably between 88° and 92°.

According to an alternative aspect, the support5may be pivoted pivoted about the rotational axis10manually.

As can be seen from theFIGS. 1A and 1B, the rotational axis10, according to the first embodiment of this invention, is in line with the measuring region, arranged centrally in the beam path of the x-rays4.

The support5carries a first receiving device11for the x-rays4as well as a second receiving device12for the x-rays4. In this example, the first receiving device11may be a removable x-ray film cassette having an x-ray film with a recording surface of, for example, 18×24 cm or 24×30 cm and the second receiving device12may be a large-surface low-resolution solid-state detector for x-rays for producing FFDM (full field digital mammography) images.

As an alternative to the x-ray film cassette with an x-ray film, a CCD sensor incorporated into an x-ray film cassette may be used. The recording surface of a CCD sensor of this kind is, at present smaller than that of an x-ray film.

As theFIGS. 1A and 1Bshow, the receiving devices11and12are arranged essentially parallel to each other and parallel to the rotational axis10of the support5. In this example, the rotational axis10is arranged between the receiving devices11and12. By pivoting the support5180° clockwise or anticlockwise about the rotational axis10, the first or the second receiving device11,12can be moved, alternately, into a measuring position.

In the measuring position, the respective receiving device11or12adjacent to the measuring region is arranged in the beam path for the x-rays4in such a way that a surface thereof is aligned towards the radiation source3. Furthermore, the beam path of the x-rays4and a surface of the receiving device11or12located in the measuring position are oriented at an angle of substantially 90°.

Thus, by pivoting the support5, the first or the second receiving surface11or12alternately come to rest on the upper side of the support5. InFIGS. 1A and 1B, the fixing of the support5and, thus, the fixing of the respective receiving device11and12in the respective measuring position is achieved via the motor8. However, alternatively, a separate fixing device can be provided, which device preferably has shielding.

InFIGS. 2A,2B and2C the support5of the medical imaging equipment1shown inFIGS. 1A and 1Bis represented in different pivot positions. These are schematic sectional views through the support5at right angles to the rotational axis10.

The support5carries a first receiving device11which may be an exchangeable x-ray film cassette, which can contain an x-ray film or a CCD sensor. In addition, the support5carries a second receiving device12which is a low resolution digital sensor for FFDM recordings.

A first or a second filter13,14is arranged in front of the x-ray film cassette11or in front of the low-resolution digital sensor12. In this example, the filters13and14are scattered radiation grids, which are each adapted to the receiving device adjacent x-ray sensor.

The support5, shown inFIGS. 2A to 2C, may carry a control device15, which is used for the automatic control of the received x-rays4. The control device15may be shared by the two receiving devices11and12. By using a shared control device15, the number of components used can be kept low. This enables the production costs to be reduced.

When an x-ray film is used in the receiving device11, it the control device15may assume the function of an automatic exposure control (AEC) detector. Thus, the control device measures the radiation received in order to calculate the correct or optimal exposure time for the x-ray film.

When a CCD sensor is used in the receiving device11or when the low resolution digital sensor12is used, the correct or optimal exposure time is automatically determined by the respective sensor. An additional AEC detector is not required. However, the control device15can be used as an additional safety device, so as to avoid unnecessary exposure to radiation if the CCD sensor or the low resolution digital sensor12fails.

As shown inFIGS. 2A to 2C, the support5carries the receiving devices11and12, together with the associated filters13and14. The rotational axis10is arranged such that a perpendicular projection16of the rotational axis10onto the receiving surface11or12, bisects the surface of the receiving device11or12, respectively. The perpendicular projection16is illustrated by a broken line in the figures.

This arrangement aligns the respective receiving device11or12centrically to the rotational axis10in the measuring position, and this makes the operation by a doctor particularly intuitive.

FIG. 2Ashows the support5in a position suitable for producing an analog (x-ray film) image of the female breast7using the x-ray film in an exchangeable receiving device11, and the control device15.

FIG. 2Bshows the support5in a center pivot position.

FIG. 2Cshows the support5in a position in which the low resolution digital sensor12is located in a measuring position in such a way that it is possible to create a digital (FFDM) image of the female breast7.

FIG. 3shows an alternative example of an arrangement of a support for receiving devices of the medical imaging equipment1, shown inFIGS. 1A and 1B.FIG. 3is a schematic sectional view perpendicular to the rotational axis10.

The support for the receiving devices shown inFIG. 3differs from the first example in that the support5′ carries a CCD sensor17for creating high-resolution detailed recordings of the female breast7, in addition to the low-resolution digital sensor12for generating FFDM images, and the scattered radiation grid14. The receiving surface of the high-resolution CCD sensor17using commercially available technology is smaller than that of the low-resolution digital sensor12.

If necessary, an antiscatter grid can also be provided in front of the CCD sensor.

A shield18, which may be a lead plate, is provided between the high-resolution CCD sensor17and the low-resolution digital sensor12, the shield also being carried by the support5′. The shield18shields the respective receiving surface17or12not located in the measuring position from the beam path of the x-rays4and in this way prevents x-rays4from being able to emerge on the underside of the support5′. In this way, a patient's exposure to radiation is reduced. Moreover, it prevents the receiving surface17or12not located in the measuring position being exposed unintentionally and also prevents this receiving surface17or12being exposed to radiation.

As an alternative to using lead for the shield18, when very soft x-rays (approximately 20-35 kV) are used, another material that is opaque to soft x-rays may be used. This is beneficial in terms of environmental protection. Soft x-rays may be used in mammography.

The rotational axis10is not arranged within the support5′ between the two receiving surfaces12and17, but outside the support5′. Thus in order to pivot the support5′ about the rotational axis10, provision is made for the use of a second bracket19. The receiving surfaces12and17may not be bisected by a respective perpendicular projection of the rotational axis10.

A construction of this kind is practical when the mechanics required for the rotational axis10cannot be provided within the support for reasons, for example, of space.

Pivoting the support5′ results in a relatively wide movement, and the two receiving devices12and17in the respective measuring position are not located in the same place but in both horizontally and vertically displaced places.

This may result in horizontal or vertical compensating devices (not shown in the figures) having to be provided in order to arrange the respective receiving device in focus in the beam path of the x-rays.

FIG. 4shows a second example of the support5″ of a receiving device of medical imaging equipment1.FIG. 4is also a cross-sectional view through the support5″ parallel to the rotational axis10.

The support5″ carries a mounting for holding an exchangeable x-ray film11′, a large-surface low-resolution digital sensor12for creating FFDM images, as well as a high-resolution CCD sensor17′ for creating detailed recordings of the female breast7. A scattered radiation grid14is provided above the low-resolution digital sensor12.

A suitably adapted filter (not shown) may also be provided above the aperture for the exchangeable x-ray film11′ and/or above the high-resolution CCD sensor17′.

The receiving devices11′,12and17′ have surfaces parallel to the rotational axis10. A perpendicular projection16,16′,16″ of the rotational axis10on the receiving device surfaces11′,12and17′ bisects the receiving device11′ and12. However, in the example shown, the receiving device17′ is not bisected.

An arrangement where a perpendicular projection16″ of the rotational axis10does not bisect the receiving device17′ may be useful as when, with the receiving device17′ in measuring position, the object for measurement7should not or cannot be arranged centrally above the rotational axis10.

The support5″ is configured so the receiving devices11′,12and17′, which it carries, are disposed in such a way that adjacent receiving devices are disposed at an angle β of essentially 60° with respect to each other.

To enable the support5″ to pivot with the minimum width of movement possible, the rotational axis10in the example shown inFIG. 4is disposed at the geometric center of the volume encompassed by the support5″ for the receiving devices11′,12and17′.

Even though the arrow depicted inFIG. 4indicates the support5″ pivoting in an anticlockwise direction about the rotational axis10, the support5″ may also be pivoted about the rotational axis10as desired in a clockwise direction or, alternately, in a clockwise and in an anticlockwise direction.

FIG. 5shows a third example of a support5′″ of the receiving devices of the medical imaging equipment1according.FIG. 5is also a schematic cross-sectional view through the support5′″ parallel to the rotational axis10.

The support5′″ carries an exchangeable removable x-ray film cassette11, a large-surface low-resolution digital sensor12for creating FFDM images, a high-definition CCD sensor17for creating detailed recordings of the female breast7and a luminescence radiography screen20. Scattered radiation grids13or14are arranged respectively in front of the exchangeable x-ray film cassette11and the low-resolution digital sensor12.

A suitably adapted scattered radiation grid may also be provided above the small-surface high-resolution CCD sensor17and also above the luminescence radiography screen20.

The pivot axis is arranged in the geometric center of the volume encompassed by the support5′″ for the receiving devices11,12,17and20. Thereby, the receiving devices11,12and17are arranged in such a way that the perpendicular projections16or16′ onto the respective receiving surfaces bisect said receiving surfaces. Adjacent receiving devices11,12,17,20make an angle γ of substantially 90° with respect to each other.

The support5′″ shown inFIG. 5and may be a compact design and create mammographic images using four different measuring methods and hence to adapt the measuring method to the respective application in an optimal manner.

In the previous examples, the use of x-ray films, low-resolution digital sensors/detectors for FFDM images, high-resolution CCD sensors for detailed recordings as well as the luminescence radiography screen as a receiving device were disclosed, it is obvious that the receiving devices can be realized by alternative measuring devices having a sensitivity to the measuring radiation that now exist or may be developed. Further, the support for the receiving devices can also carry more than four receiving devices.