HK1200298B - Apparatus and method for digital radiography - Google Patents

Description

Apparatus and method for digital radiography

Technical Field

The present invention relates to a method for digital radiography (digital radiography) by means of a combined multi-sensor X-ray imaging device, the digital radiography being capable of being performed according to a plurality of imaging modes, the method comprising the steps of:

-positioning the object between the radiation source and the X-ray detector with an object support and positioning system;

-selecting a radiographic imaging modality (modality) and a desired region of interest;

-adjusting the shape of the X-ray beam according to the selected imaging modality by means of one or more X-ray collimators;

-positioning an X-ray detector at a predetermined position in the X-ray beam;

-generating X-ray radiation by a radiation source;

-performing a movement for scanning the object while detecting X-ray radiation by means of the X-ray detector;

-performing a readout, acquisition and refinement (occlusion) of the X-ray detector image data in order to obtain a processed image or three-dimensional data set of the selected region of interest according to the selected imaging mode.

The invention also relates to a device for carrying out the method.

Background

Combined X-ray imaging devices capable of imaging according to a plurality of imaging modes are well known in the art.

From US 6118842, a dual-purpose X-ray imaging apparatus for dental and medical diagnosis is known, which is equipped with a single sensor and allows multiple imaging modes, i.e. local CT (computed tomography) imaging and panoramic imaging.

From US 6055292, another device is known which provides at least one X-ray detector which, depending on the selected imaging mode, can be positioned in a plurality of imaging positions and correspondingly exposed by a collimated X-ray beam. Further, from US 7559692 and US 7798708, an embodiment is known of a single movable cabinet containing two X-ray detectors that can be positioned depending on the imaging mode.

EP 1752099 teaches a combined panoramic and computed tomography apparatus characterized in that: the X-ray sensor portion is provided with two X-ray detectors and is rotatable about an eccentric axis, so that, depending on the selected imaging mode, different X-ray detectors are placed in the X-ray beam at a preferred distance from the source and are exposed to the radiation.

EP 1752100 teaches a combined panoramic and computed tomography apparatus characterized in that: the X-ray sensor part is provided with two X-ray detectors mounted on a rotary arm displaced by different distances relative to the source. The X-ray detector for panoramic imaging is located closer to the source and can slide out of the beam when the CT imaging mode is selected.

EP 1752099 teaches a combined panoramic, computed tomography and cephalometric (cephalometric) apparatus characterized in that: the X-ray sensor part is provided with two X-ray detectors that are rotatable about an axis or slidably displaceable, so that depending on the selected imaging mode, different X-ray detectors are placed in the X-ray beam at a preferred distance from the source and are exposed to the radiation.

US 7783002 teaches a combined panoramic and computed tomography apparatus characterized in that: a fixed CT X-ray detector, and a movable panoramic X-ray detector having a pivotal movement to rotate it out of the beam when the CT imaging mode is selected.

WO 2010/128404 teaches a combined panoramic, computed tomography and cephalometric apparatus having an elongated rotary arm and providing various arrangements for positioning the detectors in and out of the X-beam at a predetermined distance from the source by means of translation of a movable platen or by means of pivoting, including a third position in which the panoramic and CT detectors are out of the beam and a third detector for cephalometric measurements is exposed.

In the case of cephalometric imaging modalities, US 5511106 teaches a method of scanning a patient's skull by a secondary collimator located near the patient and translated by a linear movement synchronized with the movement of the detector.

US 7103141 teaches a method of modulating the radiation intensity during a head measurement scan process by adjusting the tube voltage or tube current or scan speed.

US 2009/168966 teaches a combined apparatus having multiple imaging modes in which computed tomography is incorporated, wherein the radiation field is varied according to the selected imaging mode by primary and secondary collimation mechanisms; in particular, various collimator arrangements are described, wherein the secondary collimator is basically mentioned for proximity limitation in front of the CT detector and no movable secondary collimation for head measurement scanning placed in the X-ray sensor box behind the detector with respect to the source is disclosed.

EP 1752099 teaches a combined device for panoramic and CT imaging modes, the device having an adjustable magnification, and a mounting means for attaching and detaching a suitable X-ray detector; however, it does not disclose head measurement imaging and secondary collimation for head measurement.

EP 2198783 teaches a simplified X-ray device with a fixed secondary collimator placed at the end of a rotary arm, which is used for X-ray scanning in head measurements by means of a rotational-translational movement of said rotary arm, but EP 2198783 does not teach a method for X-ray scanning in head measurements, in which the rotary arm is stationary, the secondary collimator is moved by a translational movement of a detector box, in which the secondary collimator is located in a position behind the detector with respect to the source.

In the case of cone beam CT image acquisition and reconstruction, various publications teach various methods and algorithms, including:

Med Phys.2003Oct；30(10):2758-61。

Liu V,Lariviere NR,Wang G.-CT/Micro-CT Lab,Department of Radiology,University of Iowa,Iowa City,Iowa52242,USA。

x-ray micro-CT with a displaced detector array: application to heliconic-beam recovery. In X-ray micro-CT applications, it is useful to increase the field of view by offsetting a two-dimensional (2D) detector array. In this technical recording, a brief review of the method for image reconstruction with an asymmetric 2D detector array is presented detailing the use of the relevant weighting scheme in the case of helical cone-beam scanning, and a series of numerical tests were conducted to demonstrate the helical cone-beam image reconstruction with this arrangement.

Med Phys.2002Jul；29(7):1634-6.-Wang G.-Department of Radiology,University of Iowa,Iowa City52242,USA.ge-wang@uiowa.edu

X-ray micro-CT with a displaced detector array。

Since in X-ray micro-CT applications the sample size varies, it is desirable to have a mechanism to change the field of view of the micro-CT scanner. A known approach to double the field of view diameter is to shift the detector array by 50%. In this paper, it is proposed to shift the detector array by an amount greater than 0% but less than 50% for a continuously adjustable field of view and to formulate a weighting scheme for artifact free reconstruction. Subsequently, numerical simulations were performed using Shepp-Logan model to demonstrate feasibility in fan-beam and cone-beam geometries.

Yu,L.Pelizzari,C.Pan,X.Riem,H.Munro,P.Kaissl,W.(Dept.of Radiol.,Chicago Univ.,IL,USA)

This paper appears in the Nuclear Science Symposium Conference Record,2004IEEE

Date of publication: 16-22Oct.2004volume:5-On page(s):3249 and 3252 volume.5

ISSN:1082-3654

E-ISBN:0-7803-8701-5

Print ISBN:0-7803-8700-7

INSPEC search number 8588605

Digital object identifier: 10.1109/NSSMIC.2004.1466376

Date of publication of the current version: 01August2005

Abstract

In many implementations of cone beam CT in radiotherapy for target localization, it is not uncommon for the maximum allowable field of view (FOV) to fail to cover the patient due to the limited size of the flat panel detector. In this case, the measurement results will contain truncated projections, resulting in significant artifacts in the reconstructed image. An asymmetric cone-beam configuration may be used to increase the FOV size by shifting the detector panel to one side. From the data obtained with this asymmetric configuration, the well-known algorithm (FDK) developed by Feldkamp, Davis, and Kress can be modified to reconstruct the image. However, as detector asymmetry increases, the modified FDK algorithm may produce significant aliasing artifacts. In this work, a new algorithm for image reconstruction in asymmetric cone beam CT is proposed that is capable of producing images of improved numerical properties and allows for large detector asymmetries. This asymmetric configuration and developed algorithm has been used in cone beam CT systems in radiotherapy to increase FOV size. Preliminary simulation studies were performed to verify the asymmetric configuration and proposed reconstruction algorithms.

Conebeam X-ray computed tomography with an offset detector array

Gregor,J.；Gleason,S.S.；Paulus,M.J.；

Dept.of Comput.Sci.,Tennessee Univ.,Knoxville,TN,USA

This paper appears in: image Processing,2003, ICIP2003.proceedings.2003International Conference, On page(s): II-803-6vol.3

ISSN:1522-4880

Print ISBN:0-7803-7750-8

INSPEC search number: 7978666

Digital object identifier: 10.1109/ICIP.2003.1246802

Date of publication of the current version: 24November2003

Abstract

Conventional X-ray Computed Tomography (CT) imaging is based on the assumption that the entire cross section of the object is irradiated with X-rays at each view angle. Thus requiring a large detector array when imaging a large subject. As an alternative, it is proposed to shift the detector array of normal size such that slightly more than half of the required projection data is obtained. During reconstruction, the missing data is taken into account by means of an interpolation and weighting scheme. The arithmetic method for expanding the field of view, described here in the context of the popular Feldkamp algorithm, is simple and efficient. Supporting experimental results are provided based on simulation model data and real data obtained from MicroCATTM, a circular orbit micro CT system for small animal imaging.

Comput Med Imaging Graph.1996Jan-Feb；20(1):49-57。

Cone-beam CT from width-truncated projections。

Cho PS,Rudd AD,Johnson RH。

Source

Department of Radiation Oncology,University of Washington School ofMedicine,Seattle98195-6043,USA。

Abstract

In this paper, cone beam CT techniques are reported which allow reconstruction from width truncated projections. These techniques are a variant of the Feldkamp's filtered backprojection algorithm and assume quasi-redundancy of ray integrals. Two methods were obtained and compared. The first approach involves pre-convolution weighting with truncated data. The second technique performs post-convolution weighting, preceded by a non-zero estimate of the missing information. The algorithm was tested using a three-dimensional Shepp-Logan head model. The results show that a satisfactory reconstruction can be obtained with a suitable amount of overscan. These techniques can be used to solve the problem of undersized detectors.

Phys Med Biol.2005Apr21；50(8):1805-20.Epub2005Apr6。

Exact fan-beam image reconstruction algorithm for truncatedprojection data acquired from an asymmetric half-size detector。

Leng S,Zhuang T,Nett BE,Chen GH。

Source

Department of Medical Physics,University of Wisconsin-Madison,53704,USA。

Abstract

In this paper, a new algorithm designed for the specific data truncation problem in fan beam CT is introduced. Consider a scanning arrangement in which fan beam projection data is obtained from asymmetrically positioned half-size detectors. I.e. the asymmetric detector covers only half of the scan field of view. Thus, at each view angle, the acquired fan beam projection data is truncated. This data acquisition configuration, if not invoked for explicit data rebinning (rebinning) processing, would severely disrupt many known fan-beam image reconstruction schemes, including standard Filtered Backprojection (FBP) algorithms and ultra-short scan FBP reconstruction algorithms. However, the newly proposed fan-beam image reconstruction algorithm that reconstructs an image via reflection projection image (FBPD) filtering of the differential projection data proves to survive the fan-beam data truncation problem described above. That is, with the truncated data obtained in the full scan mode (2pi angular range), the entire image can be accurately reconstructed. Small regions of interest (ROIs) can also be accurately reconstructed using truncated projection data obtained in short scan mode (less than 2pi angular range). The most important feature of the proposed reconstruction scheme is that no display data binning process is introduced. Numerical simulations were performed to validate the new reconstruction algorithm.

The first problem that the prior art does not solve is: a solution is provided that allows manual disassembly of a panoramic detector while protecting the CT detector, which is typically an area sensor of elongated dimensions and which can be conveniently displaced to a position for head measurement, allowing panoramic and cephalometric imaging modes to be performed with a single sensor, wherein the CT detector is typically extremely expensive and should not be assembled with the possibility of manual disassembly.

The second problem that the prior art does not completely solve is: in order to obtain flexibility of operation and an economical electromechanical solution, it is desirable to have an arrangement provided with a single moving means capable of performing all necessary detector positioning and scanning movements required for performing head measurements.

Among the necessary detector localizations are the local offset localizations required for carrying out a specific CT imaging mode, defined in literature as "extended field of view" (where an extended portion of the region of interest of the patient is reconstructed as a result of the acquisition of a plurality of images by offset rotation around the object.

Disclosure of Invention

Starting from the prior art, the present invention seeks to provide a method and apparatus that avoids the above-mentioned drawbacks by simplifying the structure and geometry of the imaging system.

The above object is achieved by a device and a method having the features in the independent claims. Advantageous embodiments and improvements are specified in the dependent claims.

The combined imaging apparatus of the present invention is capable of X-ray imaging of an object such as, for example, a body part (more specifically including the human skull and the ear-throat region) according to different imaging modalities.

In a preferred embodiment, a CT X-ray detector for CT imaging is provided having rectangular dimensions preferably in the range of 5X 5cm to 13X 13cm and larger.

A panoramic X-ray detector for panoramic imaging having an elongated imaging area preferably in the range of 6X 150mm is also provided.

Furthermore, a head measurement X-ray detector for head measurement imaging is provided having an elongated imaging area preferably in the range of 6X 220 mm.

In a preferred configuration intended to improve the economy of the system, the head measurement X-ray detector may also be conveniently used for panoramic imaging, thereby reducing the cost of ownership for the user. In this case, the cephalometric X-ray detector can be displaced from the panoramic position to the cephalometric position by means of a manually releasable connection.

According to this method, the CT detector is contained within a metal and/or plastic housing, and is thus protected and inaccessible to the user. A secondary collimator is also mounted within the housing adjacent the CT sensor and has an opening (aperture) sized to provide a fan-shaped X-ray beam that accurately hits a head measurement X-ray detector, typically placed at a distance of about 1.5m from the X-ray source.

A panoramic detector is also mounted on the outside of the housing adjacent to the location of the secondary collimator and is manually removable by means of an electromechanical release.

The head measurement detector is mounted on a support structure at the head measurement position, typically at a distance of about 1.5m from the X-ray source, and can also be manually disassembled by means of an electromechanical release device.

In a preferred configuration, when panoramic imaging is required, the head measurement detector is manually detached from the head measurement position and then installed in the panoramic position.

The CT detector housing (hereinafter referred to as the X-ray sensor cartridge) is horizontally movable in a direction perpendicular to the central axis of the X-ray beam by means of a motor-driven linear actuator.

In a first example according to the method, an X-ray sensor cassette horizontal movement device (25) is used to place the CT detector symmetrically horizontally aligned with the beam when the CT imaging modality is selected. The X-ray exposure and image acquisition process is then started by rotating the rotary arm around the patient and simultaneously acquiring a plurality of images according to a predetermined sequence.

In another example according to the method, an X-ray sensor cassette horizontal movement device (25) is used to place the CT detector asymmetrically horizontally aligned to the beam, i.e. partially offset with respect to the central ray of the beam, when applicable, when an "extended field of view" CT imaging modality is selected. Subsequently, the X-ray exposure and image acquisition process is started by rotating the rotary arm around the patient and simultaneously acquiring a plurality of images according to a predetermined sequence. In this case, the reconstruction algorithm will allow for a three-dimensional reconstruction of the extended region of interest of the patient.

In another example according to the method, an X-ray sensor box horizontal movement means (25) is used to place the panoramic detector symmetrically horizontally aligned beams when the panoramic imaging model is selected. Subsequently, the X-ray exposure and image acquisition process is started by rotationally translating the rotary arm around the patient and simultaneously acquiring a plurality of images according to a predetermined sequence.

In another example according to the method, the X-ray sensor cartridge horizontal moving means (25) is used to place the secondary X-ray collimator (24) in an extreme starting position for the head measurement scan when the head measurement imaging modality is selected. Subsequently, an X-ray exposure scan and an image acquisition process are started by linearly translating an X-ray sensor cartridge containing a secondary collimator (24) and a head measurement X-ray detector (9) in synchronization, and simultaneously acquiring a plurality of images according to a predetermined sequence.

In this process, a primary X-ray collimator (22) having a wide opening is fixed, and a secondary X-ray collimator (24) is moved by the movement of the X-ray sensor cartridge (23) in synchronization with the movement of the head measurement X-ray detector (9), thereby generating a moving fan-shaped X-ray beam hitting the effective area of the linear head measurement X-ray detector (9) during horizontal translation thereof.

In this manner, the motor drives for CT and panoramic sensor positioning can be advantageously used for extended field of view imaging processing and for cephalometric scanning processing.

Thus, a movable X-ray sensor cartridge containing a secondary X-ray collimator (24) placed on the rotary arm provides a simplified and economical structure that is particularly advantageous in X-ray imaging modalities such as CT imaging, panoramic imaging and cephalometric imaging.

Furthermore, various means may be used to modulate the intensity of the beam during the panoramic or cephalometric scanning process. Such means may include modulation of the tube voltage, or modulation of the tube current, or a change in scan speed, among others.

For example, in cephalometric imaging, the intensity may be increased during the transition from a soft tissue region such as the tip of the nose to a bony region of the patient's skull; in panoramic imaging, the intensity may be increased during the transition from the patient's spine.

The modulation may be according to a predetermined profile (profile) or according to a profile that is adjusted in response to an operator's selection or a particular morphological feature of the patient. For example, in cephalometric imaging, modulation may be performed in response to a measured size of the distance between the patient's nasion and ear canal.

The measurement of these morphological features may be performed in various ways, including, for example, by acquiring electrical signals from a length sensor, or by taking measurements of video images of the patient obtained.

Of course, when the modulation is performed automatically in response to the morphological characteristics of the patient, the reliability of the process and the workload of the operator can be optimized.

In another embodiment, it is also advantageous that the modulation can be performed automatically in real time in response to a feedback signal proportional to the actual or cumulative dose measured in the area of the X-ray detector corresponding to the actual exposure area of the patient. This may also follow a predetermined intensity profile which may be conveniently adjusted in response to the dose feedback signal.

Drawings

Further advantages and properties of the invention are disclosed in the following description, wherein exemplary embodiments of the invention are described in detail on the basis of the figures:

FIG. 1 is a front view of an imaging system;

FIG. 2 is a view of a rotating arm supporting an X-ray generator and an X-ray sensor cartridge;

FIG. 3 is an isometric view of a secondary collimator;

FIG. 4 is a top view showing details of a CT imaging process;

FIG. 5 illustrates details of the panoramic imaging process;

FIGS. 6a and 6b illustrate details of a head measurement imaging process;

fig. 7 illustrates details of the CT imaging process in the extended field of view modality.

Detailed Description

According to a preferred embodiment, the imaging system of the invention is based on a combined X-ray diagnostic system for panoramic, CT (computed tomography) and cephalometric examination of human skull.

Such a device is depicted in fig. 1, where a column (1) vertically supports a sliding carriage (2), which carriage (2) can slide vertically along the column to be adjusted in view of the patient height.

The carriage (2) supports the rotating arm (3) by means of a photographic (cinematic) unit (4) capable of driving said rotating arm (3) according to a rotational and translational movement.

The rotating arm (3) holds an X-ray generator (5) opposite to the panoramic X-ray detector (6a) and the CT X-ray detector (6 b).

For panoramic and CT imaging, the patient is positioned under the rotating arm (3), between the X-ray generator (5) and the X-ray detectors (6a) and (6b), and supported and aligned by a patient positioning system (7).

The carriage (2) also holds side arms (8) for head measurement imaging.

A side arm (8) holds a head measurement X-ray detector (9) and a head measurement patient positioning system (10).

For cephalometric imaging, the patient is located at the side, at an extended distance from the X-ray generator (5) and closer to the X-ray detector (9), and is supported and aligned by a patient positioning system (10).

For economy and convenience, the panoramic X-ray detector (6a) is detachable and manually displaceable by an operator to a position at which the head measures the X-ray detector (9).

Referring to fig. 2, the details of the rotating arm (3) are shown.

The X-ray generator (5) is user-inaccessible, contained in a plastic or metal housing (21), and is provided with a primary X-ray collimator (22), which primary X-ray collimator (22) limits and shapes the X-ray beam according to the selected imaging modality.

On the opposite side, the CT X-ray detector (6b) is contained within a housing defined as an X-ray sensor cartridge (23), which X-ray sensor cartridge (23) also contains a secondary collimator (24).

Outside the X-ray sensor box (23), a panoramic X-ray detector (6a) is shown.

The panoramic X-ray detector (6a) is provided with its own housing (26), which housing (26) is detachably mounted outside the X-ray sensor box (23).

The motor driver (25) allows the X-ray sensor cartridge (23) to move horizontally in a direction perpendicular to the X-ray beam.

Referring to fig. 3, the secondary collimator (24) is shown in detail.

The secondary collimator (24) is constituted by a lead plate provided with an elongated opening (31) to allow the size of the X-ray beam formed from the primary X-ray collimator (22) to be adjusted to a fan-shaped X-ray beam having a width and a height such that the X-ray beam will hit the active area of the cephalometric X-ray detector (9) accurately during the cephalometric imaging procedure.

Referring to FIG. 4, details of the CT imaging process are shown.

When the CT imaging mode and the desired region of interest are selected, the X-ray sensor cassette (23) is slid laterally (laterally) by a horizontal motor drive (25) so that the CT X-ray detector (6b) is set in a position for CT imaging, aligned symmetrically in the horizontal direction with respect to the central axis (41) of the X-ray beam.

The primary X-ray collimator (22) opening is adjusted so that the X-ray beam is rectangular in shape, having a width and a height that precisely hit the active area of the CT X-ray detector (6 b).

The patient is positioned precisely between the X-ray generator (5) and the X-ray detector (6b), fixed and aligned by a patient positioning system (7).

Under the above conditions, the rotary arm (3) starts to rotate around the patient, while the X-ray generator (5) simultaneously emits X-ray pulses and the X-ray detector (6b) image data is read out, allowing the acquisition of multiple two-dimensional views of the patient from different projection angles.

The obtained plurality of two-dimensional view data is fed to a processing algorithm which performs a three-dimensional reconstruction of the volume associated with the selected region of interest.

Referring to fig. 5, the details of the panoramic imaging process are illustrated.

When a panoramic imaging mode and a desired region of interest are selected, the X-ray sensor cartridge (23) is laterally slid by a horizontal motor drive (25) so that the panoramic X-ray detector (6a) is set in a position for panoramic imaging, symmetrically aligned in a horizontal direction with respect to a central axis (41) of the X-ray beam.

The primary X-ray collimator (22) opening is adjusted such that the X-ray beam is elongated in shape, has a height and a narrow width so as to hit the active area of the panoramic X-ray detector (6a) accurately.

The patient is positioned precisely between the X-ray generator (5) and the X-ray detector (6a), fixed and aligned by a patient positioning system (7).

Under the above conditions, the rotary arm (3) starts a rotational-translational scanning motion around the patient, while the X-ray generator (5) emits X-rays simultaneously and the X-ray detector (6a) image data is read out, allowing the acquisition and reconstruction of a two-dimensional panoramic image.

Panoramic image reconstruction (typically by shifting and adding) can be performed from the combined profile of successive images; the combined profile may be selected from preconfigured profiles or may be adjusted by the user during post-processing to optimize the enhancement of the in-focus layer for a particular anatomical region of interest.

Referring to fig. 6a and 6b, details of the head measurement imaging process are illustrated.

When the head measurement imaging mode and the desired region of interest are selected, the X-ray sensor cartridge (23) is laterally slid by the horizontal motor driver (25) so that the opening of the secondary X-ray collimator (24) is set at the start position for the head measurement imaging process.

In this imaging mode, the primary X-ray collimator (22) opening is fixedly set to define a rectangular dimension of a rectangular X-ray beam whose cross-sectional dimension in the plane of the secondary X-ray collimator (24) is fully contained within said secondary collimator.

In other words, the cross-sectional height slightly exceeds the upper and lower boundaries of the secondary collimator opening but is within the upper and lower boundaries of the secondary collimator (24), while the cross-sectional width is so large that the whole head measurement scan processing means remains contained in the secondary collimator (24) but outside the starting and ending positions of the secondary collimator opening (31).

The patient is positioned precisely between the X-ray generator (5) and the head measurement X-ray detector (9), fixed and aligned by a head measurement patient positioning system (10).

Under the above conditions, the X-ray sensor cartridge (23) starts a linear scanning motion from the start position to the end position in synchronization with a linear motion of the head measurement X-ray detector (9) from the start position (61) to the end position (62), while the X-ray generator (5) simultaneously emits X-rays and the head measurement X-ray detector (9) image data is read out, thereby allowing a two-dimensional head measurement image to be acquired and reconstructed.

Referring to fig. 7, details of a CT imaging process in an extended field of view modality are illustrated.

When an extended field of view CT imaging mode and a desired region of interest are selected, an X-ray sensor cassette (23) is laterally slid by a horizontal motor driver (25) so that a CT X-ray detector (6b) is set in a position for CT imaging, being asymmetrically aligned in a horizontal direction with respect to a central axis (41) of an X-ray beam.

The CT detector will typically be aligned laterally offset by about 25% of its width.

The primary X-ray collimator (22) opening is adjusted so that the X-ray beam is rectangular, with a width and height such that it hits the active area of the CTX-ray detector (6b) accurately.

The patient is positioned precisely between the X-ray generator (5) and the X-ray detector (6b), fixed and aligned by a patient positioning system (7).

Under the above conditions, the rotary arm (3) starts to rotate around the patient, while the X-ray generator (5) simultaneously emits X-ray pulses and the X-ray detector (6b) image data is read out, allowing acquisition of multiple two-dimensional views of the patient from different projection angles.

The obtained plurality of two-dimensional view data is fed to a processing algorithm which performs a three-dimensional reconstruction of the volume associated with the selected region of interest.

The exemplary apparatus described in the above embodiments finds useful industrial application in the fields of dentistry, oral and maxillofacial surgery, as well as implant, otolaryngology and other medical diagnostic radiographic examinations.

However, the apparatus of the present invention is not limited to medical use and may be advantageously employed in other non-medical fields requiring multiple X-ray detectors and multiple radiographic imaging modalities.

Finally, it is noted that throughout the description and claims of this application, the singular encompasses the plural unless otherwise indicated. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims (11)

1. A method for digital radiography according to a plurality of imaging modes, the method comprising the steps of:

-positioning the object between the X-ray source and the X-ray detector with the object support and positioning system;

-selecting a radiation imaging modality and a desired region of interest;

-adjusting the shape of the X-ray beam according to the selected imaging modality by means of one or more X-ray collimators;

-positioning an X-ray detector at a predetermined position in the X-ray beam;

-generating X-ray radiation by an X-ray source;

-performing a movement for scanning the object while detecting X-ray radiation by means of the X-ray detector;

performing a readout, acquisition and refinement of the X-ray detector image data to obtain a processed image or three-dimensional data set of the selected region of interest according to the selected imaging modality,

it is characterized in that

In at least one imaging modality, the X-ray detector is a large area first X-ray detector (6b) of rectangular dimensions enclosed within an X-ray sensor box (23),

the X-ray sensor cartridge (23) is equipped with at least one motor drive which provides a horizontal movement perpendicular to the reference axis of the X-ray beam and

the collimator comprises at least one secondary X-ray collimator (24) for head-measurement radiography, which at least one secondary X-ray collimator (24) is also enclosed within the X-ray sensor box (23) and at a larger distance from the X-ray source (5) than the first X-ray detector (6b) is from the X-ray source (5).

2. Method according to claim 1, wherein at least one second X-ray detector (6a) is detachably mounted on the X-ray sensor cassette (23), in particular on the side facing the X-ray source (5), for performing the imaging process according to the first imaging modality.

3. Method according to claim 2, wherein the at least one second X-ray detector (6a) is equipped with an electromechanical release device, can be manually disassembled, and is displaced back and forth from a first mounting position for imaging processing according to a first imaging modality to a second mounting position for imaging processing according to a second imaging modality.

4. The method of claim 3, wherein the first imaging modality is dental panoramic radiography and the second imaging modality is cephalometric radiography.

5. The method of claim 4, wherein the selected imaging modality is Computed Tomography (CT) with or without an extended field of view.

6. Method according to any of claims 2-5, wherein prior to the scanning movement and the X-ray exposure, a primary X-ray collimator (22) is set to produce an elongated opening of a fan-shaped X-ray beam, and by a horizontal lateral movement of the X-ray sensor cartridge (23) the second X-ray detector (6a) is moved to an exposure position horizontally symmetrically aligned with the X-ray beam for a dental panoramic imaging process.

7. Method according to any of claims 1-5, wherein prior to the scanning movement and the X-ray exposure, a primary X-ray collimator (22) is set to produce a rectangular opening of a rectangular X-ray beam, and by a horizontal lateral movement of the X-ray sensor cartridge (23) the first X-ray detector (6b) is moved to an exposure position horizontally symmetrically aligned with the X-ray beam for a computerized tomographic imaging process.

8. Method according to any of claims 1-5, wherein prior to the scanning movement and the X-ray exposure the primary X-ray collimator (22) is set to a rectangular opening producing a rectangular X-ray beam and the first X-ray detector (6b) is moved to an exposure position horizontally asymmetrically aligned to the X-ray beam by a horizontal lateral movement of the X-ray sensor cartridge (23) for a computerized tomography process with an extended field of view.

9. Method according to any one of claims 1-5, wherein, prior to the scanning movement and X-ray exposure, a primary X-ray collimator (22) is fixedly set to a rectangular opening producing a rectangular X-ray beam, a secondary X-ray collimator (24) has a longitudinally elongated opening producing a fan-shaped X-ray beam and is moved to a starting position by a horizontal transverse movement of an X-ray sensor cartridge (23) for a head measurement imaging process.

10. Method according to claim 9, wherein the head measurement imaging process is performed by a synchronized horizontal traverse of the X-ray sensor cartridge (23) and the head measurement X-ray detector (9), the horizontal traverse of the X-ray sensor cartridge (23) correspondingly moving the fan-shaped X-ray beam generated by the opening of the second X-ray collimator (24).

11. An apparatus for performing digital radiography according to a plurality of imaging modes, comprising:

-means for positioning the object between an X-ray source (5) and an X-ray detector;

-means for selecting a radiation imaging modality and a desired region of interest;

-means for adjusting the shape of the X-ray beam according to the selected imaging modality by means of one or more X-ray collimators;

-means for positioning the X-ray detector in a predetermined position in the X-ray beam;

-means for generating X-ray radiation by an X-ray source;

-means for performing a combined movement of the source and the detector for scanning the object while detecting X-ray radiation by means of the X-ray detector;

means for performing readout, acquisition and refinement of the X-ray detector image data to obtain a processed image or three-dimensional data set of the selected region of interest according to the selected imaging mode,

it is characterized in that

There is at least one large-area first X-ray detector (6b) of rectangular dimensions enclosed in an X-ray sensor box (23),

the X-ray sensor cartridge (23) is equipped with at least one motor drive which provides a horizontal movement perpendicular to the reference axis of the X-ray beam and

the collimator comprises at least one secondary X-ray collimator (24) for head-measurement radiography, which at least one secondary X-ray collimator (24) is also enclosed within the X-ray sensor box (23) and at a larger distance from the X-ray source (5) than the first X-ray detector (6b) from the X-ray source (5), and

the device is arranged to perform the method according to any one of claims 1-10.