X-RAY SYSTEM AND METHOD FOR PRODUCING X-RAY
IMAGE DATA
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to X-ray imaging systems and
more particularly to X-ray imaging system using digital detectors.
[0002] The advent of digital X-ray detectors has brought enhanced workflow and
high image quality to medical imaging. However, many of the earlier radiographic
imaging systems employ conventional X-ray imaging using film and/or computed
radiography. In order to obtain images from these systems, the imaging medium must
be transported and processed after each exposure, resulting in a time delay in
obtaining the desired images. Digital radiography provides an alternative that allows
the acquisition of image data and reconstructed images on the spot for quicker
viewing and diagnosis. However, the cost of replacing the earlier conventional
radiographic imagining systems with digital radiographic imaging systems may be
imposing to a hospital or tertiary care medical center. Hence, the need to retrofit the
earlier radiographic imaging systems for digital radiography in a cost effective
manner involving as few components of the systems as possible.
BRIEF DESCRIPTION OF THE INVENTION
[0003] In accordance with one embodiment, an X-ray imaging method includes
performing an X-ray exposure via an X-ray radiation source responsive to a source
controller. The method also includes sampling X-ray image data via a digital detector
without communication of timing signals from the source controller. The method
further includes combining the sampled X-ray image data of at least one imaging
frame or two or more imaging frames with at least one of the frames spanning a
duration in which the exposure occurred, to produce X-ray image data capable of
being reconstructed into a user-viewable image.
[0004] In accordance with another embodiment, an X-ray imaging method
includes performing an X-ray exposure via an X-ray radiation source. The method
also includes sampling X-ray image data via a digital detector without a priori
knowledge of beginning and ending times of the X-ray exposure. The method further
includes determining beginning and ending frames of the X-ray image data. The
method yet further includes combining the sampled X-ray image data of at least one
imaging frame or two or more imaging frames with at least one of the frames
spanning a duration in which the exposure occurred, to produce X-ray image data
capable of being reconstructed into a user-viewable image.
[0005] In accordance with a further embodiment, the X-ray imaging system
includes an X-ray radiation source, a source controller coupled to the source and
configured to command X-ray emission of X-rays for image exposures, and a digital
X-ray detector configured to sample X-ray image data without communication from
the source controller. The system also includes a portable detector control device
configured to communicate instructions to the detector for acquisition of the X-ray
image data and to receive the X-ray image data from the detector for processing and
preview. At least one of the detector, the portable detector control device, and a
processing system in communication with the detector and/or the portable detector
control device is configured to combine the sampled X-ray image data of at least one
imaging frame or two or more imaging frames with at least one of the frames
spanning a duration in which the exposure occurred, to produce X-ray image data
capable of being reconstructed into a user-viewable image.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] These and other features, aspects, and advantages of the present invention
will become better understood when the following detailed description is read with
reference to the accompanying drawings in which like characters represent like parts
throughout the drawings, wherein:
[0007] FIG. 1 is a perspective view of an exemplary fixed X-ray system, equipped
in accordance with aspects of the present technique;
[0008] FIG. 2 is a perspective view of an exemplary mobile X-ray system,
equipped in accordance with aspects of the present technique;
[0009] FIG. 3 is a diagrammatical overview of the X-ray system in FIGS. 1 and 2;
[0010] FIG. 4 is a diagrammatical representation of functional components in a
detector of the system of FIGS. 1-3;
[0011] FIG. 5 is a perspective view of the two-way interaction between the
detector and a portable detector control device, in accordance with aspects of the
present technique;
[0012] FIG. 6 is a flow diagram of a method for workflow between the detector
and the portable detector control device, in accordance with aspects of the present
technique;
[0013] FIG. 7 is a diagrammatical representation of sampling X-ray image data
from two imaging frames, in accordance with aspects of the present technique;
[0014] FIG. 8 is a diagrammatical representation of sampling and combining X-ray
image data from three imaging frames, in accordance with aspects of the present
technique;
[0015] FIG. 9 is a diagrammatical representation of sampling and combining X-ray
image data from one imaging frame, in accordance with aspects of the present
technique;
[0016] FIG. 10 is a flow diagram of a method for sampling and combining X-ray
image data to produce X-ray image data capable of being reconstructed into a userviewable
image, in accordance with aspects of the present technique;
[0017] FIG. 11 is a diagrammatical representation of workflow during an
acquisition sequence in which both image data and offset data are acquired for
producing user-viewable images, in accordance with aspects of the present technique;
[0018] FIG. 12 is a diagrammatical representation of an acquisition sequence in
which different voltages are applied to reduce transistor leakage while sampling
image data, in accordance with aspects of the present technique; and
[0019] FIG. 13 is a flow diagram of a method for sampling data from the detector
prior to and after an X-ray exposure while applying different voltages to reduce
transistor leakage, in accordance with aspects of the present technique.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Referring generally to FIG. 1, an X-ray system is represented, referenced
generally by reference numeral 10. In the illustrated embodiment, the X-ray system
10, as adapted, is a digital X-ray system. The X-ray system 10 is designed both to
acquire image data and to process the image data for display in accordance with the
present technique. Throughout the following discussion, however, while basic and
background information is provided on the digital X-ray system used in medical
diagnostic applications, it should be born in mind that aspects of the present
techniques may be applied to digital detectors, including X-ray detectors, used in
different settings (e.g., projection X-ray, computed tomography imaging,
tomosynthesis imaging, etc.) and for different purposes (e.g., parcel, baggage, vehicle
and part inspection, etc.).
[0021] In the embodiment illustrated in FIG. 1, the X-ray system 10 includes an
imaging system 12. The imaging system 12 may be a conventional analog imaging
system, retrofitted for digital image data acquisition and processing as described
below. In one embodiment, the imaging system 12 may be a stationary system
disposed in a fixed X-ray imaging room, such as that generally depicted in and
described below with respect to FIG. 1. It will be appreciated, however, that the
presently disclosed techniques may also be employed with other imaging systems,
including mobile X-ray units and systems in other embodiments. The imaging system
12 includes an overhead tube support arm 14 for positioning a radiation source 16,
such as an X-ray tube, and a collimator 18 with respect to a patient 20 and a detector
22. The detector 22 includes a digital X-ray detector. In some embodiments, the
detector 22 may be selected from a plurality of detectors 22, represented by detector
24, from a dock 26 (e.g., charging dock). Each detector 22 of the plurality of
detectors 22 may be labeled and designed for a particular type of imaging (e.g.,
fluoroscopic and radiographic imaging). The detector 22 is configured to acquire Xray
image data without communication from a controller of the X-ray radiation source
16. In other words, the detector 22 is without communication of timing signals from
the controller of the source 16 as to an X-ray exposure. As a result, in preparation for
acquiring X-ray image data the detector 22 is configured to continuously sample data
prior to and during an X-ray exposure. Also, the detector 22 is configured to combine
multiple frames that include imaging data to generate X-ray images. In addition, the
detector 22 is configured to at least partially process X-ray image data.
[0022] In one embodiment, the imaging system 12 may be used in consort with
one or both of a patient table 28 and a wall stand 30 to facilitate image acquisition.
Particularly, the table 28 and the wall stand 30 may be configured to receive detector
22. For instance, detector 22 may be placed on an upper, lower or intermediate
surface of the table 28, and the patient 20 (more specifically, an anatomy of interest of
the patient 20) may be positioned on the table 28 between the detector 22 and the
radiation source 16. Also, the wall stand 30 may include a receiving structure 32 also
adapted to receive the detector 22, and the patient 20 may be positioned adjacent the
wall stand 30 to enable the image data to be acquired via the detector 22. The
receiving structure 32 may be moved vertically along the wall stand 30.
[0023] Also depicted in FIG. 1, the imaging system 12 includes a workstation 34,
display 36, and printer 37. In one embodiment, the workstation 34 may include or
provide the functionality of the imaging system 12 such that a user 38, by interacting
with the workstation 34 may control operation of the source 16 and detector 22. In
other embodiments, the functions of the imaging system 12 may be decentralized,
such that some functions of the imaging system 12 are performed at the workstation
34 (e.g., controlling operation of the source 16, while other functions (e.g., controlling
operation of the detector 22) are performed by another component of the X-ray
system 10, such as a portable detector control device 40. The portable detector
control device 40 may include a personal digital assistant (PDA), palmtop computer,
laptop computer, smart telephone, tablet computer such as an iPad™, or any suitable
general purpose or dedicated portable interface device. The portable detector control
device 40 is configured to be held by the user 38 and to communicate wirelessly with
the detector 22. It is noted that the detector 22 and portable detector control device 40
may utilize any suitable wireless communication protocol, such as an IEEE 802.15.4
protocol, an ultra wideband (UWB) communication standard, a Bluetooth
communication standard, or any IEEE 802.1 1 communication standard.
Alternatively, the portable detector control device may be configured to be tethered or
detachably tethered to the detector 22 to communicate via a wired connection.
[0024] The portable detector control device 40 is also configured to communicate
instructions (e.g., detector operating mode) to the detector 22 for the acquisition of Xray
image data. In turn, the detector 22 is configured to prepare for an X-ray exposure
in response to instructions from the portable detector control device 40, and to
transmit a detector ready signal to the device 40 indicating that the detector 22 is
prepared to receive the X-ray exposure. The device 40 may also be configured to
communicate patient information or X-ray technique information to the detector 22.
Similar to the detector 22, the device 40 may be without communication from the
controller of the X-ray source 16. Further, the portable detector control device 40 is
configured to receive X-ray image data from the detector 22 for processing and image
reconstruction. Indeed, both the detector 22 and the portable detector control device
40 are configured to at least partially process the X-ray image data. However, in
certain embodiments, the detector 22 and/or the portable detector control device 40
are configured to fully process the X-ray image data. Also, the detector 22 and/or the
device 40 is configured to generate a DICOM compliant data file based upon the Xray
image data, patient information, and other information. Further, the detector 22
and/or the device 40 is configured to wirelessly transmit (or via a wired connection)
processed X-ray image data (e.g., partially or fully processed X-ray image data) to an
institution image review and storage system over a network 42. The institution image
review and storage system may include a hospital information system (HIS), a
radiology information system (RIS), and/or picture archiving communication system
(PACS). In some embodiments, the institution image review and storage system may
process the X-ray image data. In one embodiment, the workstation 34 may be
configured to function as a server of instructions and/or content on a network 42 of
the medical facility. The detector 22 and/or device 40 are also configured to transmit,
via a wired or wireless connection, processed X-ray images to the printer 37 to
generate a copy of the image.
[0025] The portable detector control device 40 includes a user-viewable screen 44
and is configured to display patient data and reconstructed X-ray images based upon
X-ray image data on the screen 44. The screen 44 may include a touch-screen and/or
input device (e.g., keyboard) configured to input data (e.g., patient data) and/or
commands (e.g., to the detector). For example, the device 40 may be used to input
patient information and other imaging related information (e.g., type of source 16,
imaging parameters, etc.) to form a DICOM image header. In one embodiment, the
patient information may be transferred from a patient database via a wireless or wired
connection from the network or the workstation 34 to the device 40. The detector 22
and/or device may incorporate the information for the image header with the X-ray
image to generate the DICOM compliant data file. Also, the device 40 may be used
to navigate X-ray images displayed on the screen 44. Further, the device 40 may be
used to modify the X-ray images, for example, by adding position markers (e.g., "L'7
"R" for left and right, respectively) onto the image. In one embodiment, metal
markers may be placed on the detector 22 to generate position markers.
[0026] In one embodiment, the imaging system 12 may be a stationary system
disposed in a fixed X-ray imaging room, such as that generally depicted in and
described above with respect to FIG. 1. It will be appreciated, however, that the
presently disclosed techniques may also be employed with other imaging systems,
including mobile X-ray units and systems, in other embodiments.
[0027] For instance, as illustrated in the X-ray system of FIG. 2, the imaging
system 1 may be moved to a patient recovery room, an emergency room, a surgical
room, or any other space to enable imaging of the patient 20 without requiring
transport of the patient 20 to a dedicated (i.e., fixed) X-ray imaging room. The
imaging system 12 includes a mobile X-ray base station 39 and detector 22. Similar
to above, the imaging system 12 may be a conventional analog imaging system,
retrofitted for digital image data acquisition and processing. In one embodiment, a
support arm 4 1 may be vertically moved along a support column 43 to facilitate
positioning of the radiation source 16 and collimator 18 with respect to the patient 20.
Further, one or both of the support arm 4 1 and support column 43 may also be
configured to allow rotation of the radiation source 16 about an axis. Further, the Xray
base station 39 has a wheeled base 45 for movement of the station 39. Systems
electronic circuitry 46 with a base unit 47 both provides and controls power to the Xray
source 16 and the wheeled base 45 in the imaging system 12. The base unit 47
also has the operator workstation 34 and display 36 that enables the user 38 to operate
the X-ray system 10. The operator workstation 34 may include buttons, switches, or
the like to facilitate operation of the X-ray source 16. Similar to the X-ray system 10
in FIG. 1, the system 10 includes the portable control device 40. The detector 22 and
portable control device 40 are as described above. In the X-ray system, the patient 20
may be located on a bed 49 (or gurney, table or any other support) between the X-ray
source 16 and the detector 22 and subjected to X-rays that pass through the patient 20
and are received by the detector 22.
[0028] FIG. 3 is a diagrammatical overview of the X-ray system 10 in FIGS. 1 and
2 illustrating the components of the system 10 in more detail. The imaging system 10
includes the X-ray radiation source 16 positioned adjacent to a collimator 18.
Collimator 18 permits a stream of radiation 48 to pass into a region in which a subject
20, such as a human patient 20, is positioned. A portion of the radiation 50 passes
through or around the subject 20 and impacts the digital X-ray detector 22. As
described more fully below, detector 22 converts the X-ray photons received on its
surface to lower energy photons, and subsequently to electric signals which are
acquired and processed to reconstruct an image of the features within the subject 20.
[0029] The source 16 is coupled to a power supply 52 which furnishes power for
examination sequences. The source 16 and power supply 52 are coupled to a source
controller 54 configured to command X-ray emission of X-rays for image exposures.
As mentioned above, the detector 22 is configured to acquire X-ray image data
without communication from the source controller 54. Instead, the detector 22 is
responsive to the portable detector control device 40 configured to communicate
instructions the detector 22 for acquisition of the X-ray image data. In addition, the
portable detector control device 40 is configured to receive the X-ray image data from
the detector 22 for processing and imaging reconstruction.
[0030] The detector 22 includes a wireless communication interface 56 for wireless
communication with the device 40, as well as a wired communication interface 58, for
communicating with the device 40 when it is tethered to the detector 22. The detector 22
and the device may also be in communication with the institution image review and
storage system over the network 42 via a wired or wireless connection. As mentioned
above, the institution image review and storage system may include PACS 60, RIS 62,
and HIS 64. It is noted that the wireless communication interface 56 may utilize any
suitable wireless communication protocol, such as an ultra wideband (UWB)
communication standard, a Bluetooth communication standard, or any 802.1 1
communication standard. Moreover, detector 22 is coupled to a detector controller 66
which coordinates the control of the various detector functions. For example, detector
controller 66 may execute various signal processing and filtration functions, such as for
initial adjustment of dynamic ranges, interleaving of digital image data, and so forth.
The detector controller 66 is responsive to signals from the device 40. The detector
controller 66 is linked to a processor 68. The processor 68, the detector controller 66,
and all of the circuitry receive power from a power supply 70. The power supply 70
may include one or more batteries.
[0031] Also, the processor 68 is linked to detector interface circuitry 72. The
detector 22 converts X-ray photons received on its surface to lower energy photons. The
detector 22 includes a detector array 74 that includes an array of photodetectors to
convert the light photons to electrical signals. Alternatively, the detector 22 may convert
the X-ray photons directly to electrical signals. These electrical signals are converted to
digital values by the detector interface circuitry 72 which provides the values to the
processor 68 to be converted to imaging data and sent to the device 40 to reconstruct an
image of the features within the subject 20. In one embodiment, the detector 22 may at
least partially process or fully process the imaging data. Alternatively, the imaging data
may be sent from the detector 22 to a server to process the imaging data.
[0032] The processor 68 is also linked to an illumination circuit 76. The detector
controller 66, in response to a signal received from the device 40, may send a signal to
the processor 68 to signal the illumination circuit 76 to illuminate a light 78 to indicate
the detector 22 is prepared to receive an X-ray exposure in response to the signal.
Indeed, in response to a signal from the device 40, the detector 22 may be turned on or
awoken from an idle state. Alternatively, the detector 22 may be turned on directly or
awoken from an idle state by the user (e.g., pressing an on/off button located on the
detector 22).
[0033] Further, the processor is linked to a memory 80. The memory 80 may store
various configuration parameters, calibration files, and detector identification data. In
addition, the memory 80 may store patient information received from the device 40 to be
combined with the image data to generate a DICOM compliant data file. Further, the
memory 80 may store sampled data gathered during the imaging mode as well as X-ray
images. As mentioned above, in some embodiments, the device 40 may conduct the
image processing and incorporate a DICOM header to generate a DICOM compliant
data file.
[0034] FIG. 4 is a diagrammatical representation of functional components of
digital detector 22. As illustrated, detector control circuitry 84 receives DC power
from a power source, represented generally at reference numeral 86. Detector control
circuitry 84 is configured to originate timing and control commands for row and
column electronics used to acquire image data during data acquisition phases of
operation of the system. Circuitry 84 therefore transmits power and control signals to
reference/regulator circuitry 88, and receives digital image pixel data from circuitry
88.
[0035] In a present embodiment, detector 22 consists of a scintillator that converts
X-ray photons received on the detector surface during examinations to lower energy
(light) photons. An array of photodetectors then converts the light photons to
electrical signals which are representative of the number of photons or the intensity of
radiation impacting individual pixel regions or picture elements of the detector
surface. In certain presently contemplated, the X-ray photons may be directly
converted to electrical signals. Readout electronics convert the resulting analog
signals to digital values that can be processed, stored, and displayed, such as on
device 40 following reconstruction of the image. In a present form, the array of
photodetectors is formed of amorphous silicon. The array of photodetectors or
discrete picture elements is organized in rows and columns, with each discrete picture
element consisting of a photodiode and a thin film transistor. The cathode of each
diode is connected to the source of the transistor, and the anodes of all diodes are
connected to a negative bias voltage. The gates of the transistors in each row are
connected together and the row electrodes are connected to the scanning electronics as
described below. The drains of the transistors in a column are connected together and
the electrode of each column is connected to an individual channel of the readout
electronics.
[0036] As described in greater detail below, the detector control circuitry 84 is
configured to sample data from the discrete picture elements prior to and during
receipt of X-ray radiation. Also, the detector control circuitry 84 is configured to
apply a first voltage to transistors of the discrete picture elements prior to receipt of
X-ray radiation (e.g., when the detector 22 maintains idle mode). Additionally, the
detector control circuitry 84 is configured to sample data from the discrete picture
elements in preparation for acquisition of X-ray image data while applying a second
voltage, higher than the first voltage, to transistors of the discrete picture elements not
then being sampled prior to receipt of X-ray radiation. Sampled data collected prior
to receipt of the X-ray radiation may be stored by the detector control circuitry 84 for
use in reconstruction of a user-viewable image from the X-ray image data. Further,
the detector control circuitry 84 is configured to sample data, including X-ray image
data, from the discrete picture elements during receipt of X-ray radiation while
applying the second voltage to the transistors of the discrete picture elements not then
being sampled. Following termination of the receipt of X-ray radiation the detector
control circuitry is configured to resume application of the first voltage to the
transistors of the discrete picture elements.
[0037] Turning back to the embodiment illustrated in FIG. 4, by way of example, a
row bus 90 includes a plurality of conductors for enabling readout from various rows
of the detector 22, as well as for disabling rows and applying a charge compensation
voltage to selected rows, where desired. A column bus 92 includes additional
conductors for commanding readout from the columns while the rows are sequentially
enabled. Row bus 90 is coupled to a series of row drivers 94, each of which
commands enabling of a series of rows in the detector 22. Similarly, readout
electronics 96 are coupled to column bus 92 for commanding readout of all columns
of the detector.
[0038] In the illustrated embodiment, row drivers 94 and readout electronics 96 are
coupled to a detector panel 98 which may be subdivided into a plurality of sections
100. Each section 100 is coupled to one of the row drivers 94, and includes a number
of rows. Similarly, each column driver 96 is coupled to a series of columns. The
photodiode and thin film transistor arrangement mentioned above thereby define a
series of pixels or discrete picture elements 102 which are arranged in rows 104 and
columns 106. The rows and columns define an image matrix 108, having a height
110 and a width 112.
[0039] As also illustrated in FIG. 4, each picture element 102 is generally defined
at a row and column crossing, at which a column electrode 114 crosses a row
electrode 116. As mentioned above, a thin film transistor 118 is provided at each
crossing location for each picture element, as is a photodiode 120. As each row is
enabled by row drivers 94, signals from each photodiode 120 may be accessed via
readout electronics 96, and converted to digital signals for subsequent processing and
image reconstruction. Thus, an entire row of picture elements 102 in the array is
controlled simultaneously when the scan line attached to the gates of all the transistors
118 of picture elements 102 on that row is activated. Consequently, each of the
picture elements 102 in that particular row is connected to a data line, through a
switch, which is used by the readout electronics to restore the charge to the
photodiodel20.
[0040] It should be noted that in certain systems, as the charge is restored to all the
picture elements 102 in a row simultaneously by each of the associated dedicated
readout channels, the readout electronics is converting the measurements from the
previous row from an analog voltage to a digital value. Furthermore, the readout
electronics may transfer the digital values from rows previous to the acquisition
subsystem, which will perform some processing prior to displaying a diagnostic
image on a monitor or writing it to film.
[0041] The circuitry used to enable the rows may be referred to in a present
context as row enable or field effect transistor (FET) circuitry based upon the use of
field effect transistors for such enablement (row driving). The FETs associated with
the row enable circuitry described above are placed in an "on" or conducting state for
enabling the rows, and are turned "off or placed in a non-conducting state when the
rows are not enabled for readout. Despite such language, it should be noted that the
particular circuit components used for the row drivers and column readout electronics
may vary, and the present invention is not limited to the use of FETs or any particular
circuit components.
[0042] As mentioned above, the detector 22 is without communication from the
source controller 54 and, thus, is without a priori knowledge of the beginning and
ending times of an exposure. In one embodiment, the detector 22is configured to
keep detecting the beginning and ending of the X-ray exposure automatically and
form an X-ray image without communication with the detector control device 40. In
another embodiment, the detector 22 is configured to stay in idle power mode and
switch to imaging power mode after receiving a command from the detector control
device 40. The detector 22 starts detecting the beginning and ending of the X-ray
exposure after it is switched into full power mode. This results in a unique workflow
dynamic between the X-ray system 12, detector 22, and portable detector controller
device 40 as illustrated in FIGS. 5 and 6. FIG. 5 is a perspective view of the two-way
interaction between the detector 22 and the portable detector control device 40. FIG.
5 illustrates the imaging system 12 with the patient 20 located on the table 28 between
the X-ray source 16 and the detector 22. Here again, imaging system 12 may be a
fixed or mobile system. FIG. 6 is a flow diagram of a method 124 for workflow
between the detector 22 and the portable detector control device 40. To begin, the
user turns on the detector 22 (block 126). The detector 22 maintains an idle mode in
the on condition. As illustrated in FIG. 5, the detector 22 is located beneath the
subject 20. Prior to or subsequent to turning on the detector 22, the user inputs patient
information or other information (e.g., X-ray technique) related to the imaging (e.g.,
parameters of the image) into the device 40 (block 128). In some embodiments, the
detector control device 40 may transmit the information to the detector 22, e.g., to
form the DICOM compliant data file. In some other embodiments, the DICOM
compliant data file is formed in the detector control device 40 so that no need to
transfer the patient information to the detector 22.
[0043] The user commands a detector preparation signal from the device 40 to the
detector 22 (block 130). Once the detector 22 receives the command to prepare from
the device 40, the detector 22 prepares for the acquisition of X-ray image data.
Specifically, the detector 22 switches from the idle mode to imaging power mode and
begins scrubbing (i.e., preparing and refreshing the detector circuitry) the panel of the
detector 22 to equilibrate the panel. After scrubbing, the detector 22 reads or acquires
one or more offset frames prior to exposure. In particular, the detector 22 prepares for
exposure by initiating sampling of data from a matrix of detector elements. After
preparation, the detector 22 sends to the device 40 the detector ready signal (block
132). In one embodiment, the detector 22 may also provide a visible indication (e.g.,
flashing light) or an audio indication to indicate the detector is ready. In another
embodiment, the detector control device 40 may provide a visible indication and/or
audio indication. The user then commands the X-ray radiation source 16 to perform
an X-ray exposure via the source controller 54 coupled to the source 16 (block 134).
[0044] During and after the exposure, the detector 22 samples data from the matrix
of detector elements. In certain embodiments, the detector 22 at least partially
processes the X-ray image data (block 136). Alternatively, the detector 22 may
completely process the X-ray image data. Processing includes determining when the
exposure begins and ends based upon comparison of the sampled image data
generated by the detector 22. As described in greater detail below, the sampled image
data may be collected from one or more frames and combined to generate the
reconstructed image. The detector 22 ceases sampling after determining the end of
the exposure and after sampling all of the X-ray image data from the frames. After
and during the exposure, the detector control device 40 acquires X-ray image data
from the detector 22 (block 138) upon which the detector 22 shifts from imaging
power mode to idle mode. In certain embodiments, the device 40 at least partially
processes the X-ray image data (block 140). In some embodiments, the device 40
completely processes the X-ray image data. Alternatively, the device 40 acquires
completely processed X-ray image data from the detector. In other embodiments,
neither the detector 22 nor the device 24 completely process the X-ray image data, but
send the X-ray image data to the institution image review and storage system for
subsequent processing.
[0045] As seen in FIG. 5, a reconstructed image 122 based upon the X-ray image
data is displayed (block 142) on the screen 44 of the device 40. Indeed, the
reconstructed image 122 may be displayed on the device 40 while the imaging subject
20 is present in a location wherein the X-ray image data is acquired. After displaying
the image 122 on the device 40, the user determines whether the image is acceptable
(block 144). If the image is not acceptable due to positioning issues, the imaging
subject 20 may be repositioned (block 146) for a further exposure. If the image is
acceptable, the user may select the interested portion of image, add the "L" and/or
"R" position mark, and transmit the processed X-ray image data to the institution
image review and storage system (block 148) via the detector 22 and/or device 40.
[0046] Since the detector 22 is without communication of timing signals from the
source controller 54 as to performance of the exposure via the source 16, the detector
samples data prior to, during, and after the exposure from one or more frames (e.g.,
offset and imaging frames). The length of an X-ray exposure is dependent on
numerous factors such as the type of X-ray examination and the size of the imaging
subject. In certain instances, the exposure may overlap frames and the sampled X-ray
data from at least two imaging frames may need to be combined. However, to do this
beginning and ending frames that span at least the duration of the exposure need to be
determined.
[0047] FIG. 7 is a diagrammatical representation of sampling and combining X-ray
image data when the exposure occurs in a single readout or sampling period. FIG. 7
illustrates multiple frames 150 obtained from sampling the matrix of detector
elements. The frames 150 include offset frames 152 and 154 and imaging frames 156
and 158. The offset-corrected X-ray image is generated by combining sampled data
from imaging frames 156 and 158 with sampled data (e.g., offset data from offset
frame 152) gathered prior to obtaining imaging frame 156. Offset frame 152 is
acquired prior to the initiation of the exposure. Offset frame 154 is acquired after the
exposure ends and the frames 150 include no more image data. Neither of the offset
frames 152 and 154 includes image data.
[0048] To determine the beginning and ending of the exposure and the imaging
data, a row average of each frame 150 is obtained. The row average reflects the
average amount of charge restored to each detector element within a row of detector
elements of the detector array to fully charge the detector elements. Plot 159 from top
to bottom indicates the row average of each row along the frames 150. The row
average in offset frame 152 and a top portion 160 of imaging frame 156 is negligible,
as indicated by portion 162 of the plot 159 since no exposure has occurred and the
detector elements remain fully charged. The beginning and ending of the exposure is
marked by lines 164 and 166, respectively. At line 164, 0 percent of the exposure
(i.e., percent of length of total exposure) has occurred, while 100 percent of the
exposure has occurred at line 166. Correspondingly, during the exposure, the row
average linearly increases, indicated by portion 168 of the plot 159, as the rows are
sequentially read within region 170. More specifically, the row average increases in
portion 168 because each subsequent row is exposed to a greater percentage of the
exposure and the detector elements within those rows require the restoration of more
charge. For example, the first row read after the exposure begins may be subjected to
10 percent of exposure before being read, while the last row read may be subjected to
100 percent of the exposure before being read.
[0049] Since the exposure ended within a single sampling or reading period, both
imaging frames 156 and 158 include image data indicated by the cross-hatched
regions 172 and 174, respectively. Flat portion 176 of plot 159 indicates the rows in
regions 178 and 180 of imaging frames 156 and 158, respectively, have been exposed
to 100 percent of the exposure prior to being read. Lines 182 and 184 indicate the
beginning and ending of reading rows in region 186 of frame 158 corresponding to
region 170 of frame 156. As indicated by portion 188 of the plot 159, the row
average linearly decreases as the rows are sequentially read within region 186. More
specifically, the row average decreases in region 186 because each subsequent row
was exposed to a lesser percent of the exposure after the initial reading of the rows in
region 170 of reading frame 156. In other words, the row average in region 186
reflects image data from residual exposure subsequent to the last reading of the rows.
For example, the first row read in region 180 of frame 158 may have been subjected
to 90 percent of the exposure after the initial reading of the first row in region 170 of
frame 156, while the last row read in region 180 may have been subjected to 0 percent
of exposure after the initial reading of the last row in region 170 of frame 156.
Portion 190 of plot 159 indicates the row average 156 in a bottom portion 192 of
imaging frame 158 and the offset frame 154 is negligible since the detector elements
have been recharged since last being read. As a result, by determining the row
average, the beginning and ending of the exposure may be determined as well as the
beginning and ending of the imaging data.
[0050] To obtain the X-ray image all of the frames 150 including image data (e.g.,
frames 156 and 158) are combined (i.e., added). To obtain the offset-corrected X-ray
image, the total number of frames 150 used to make the X-ray image (e.g., two,
frames 156 and 158) are multiplied time the calculated offset image (e.g., offset frame
152) and subtracted from the X-ray image to form the offset corrected X-ray image.
[0051] The row average may also be used when the exposure spans more than one
reading or sampling period. FIG. 8 is a diagrammatical representation of sampling
and combining X-ray image data when the exposure occurs over two readout or
sampling periods. Similar to FIG. 7, FIG. 8 illustrates multiple frames 150 obtained
from sampling the matrix of detector elements. The frames 150 include offset frames
194 and 196 and imaging frames 198, 200, and 202. Offset frame 194 is acquired
prior to the initiation of the exposure. Offset frame 196 is acquired after the exposure
ends and the frames 150 include no more image data. As above, neither of the offset
frames 194 and 196 includes image data.
[0052] As in FIG. 7, a row average is obtained for each frame 150 in FIG. 8. Plot
204 from top to bottom indicates the row average of each row along the frames 150.
The row average in offset frame 194 and a top portion 206 of imaging frame 198 is
negligible, as indicated by portion 208 of the plot 204 since no exposure has occurred
and the detector elements remain fully charged. The beginning and ending of the
exposure is marked by lines 210 and 212, respectively. At line 210, 0 percent of the
exposure has occurred, while 100 percent of the exposure has occurred at line 212.
As illustrated, the exposure spans two sampling periods and, thus, two imaging
frames 198 and 200. Similar to FIG. 7, FIG. 8 includes row averages that linearly
increase as indicated by portion 214 of the plot 204 corresponding to regions 216 and
218 of imaging frames 198 and 200. Also, flat portion 220 of plot 204 corresponds to
region 222 of imaging frame 200 and indicates those rows are exposed to 100 percent
of exposure prior to being read. Portion 220 is far shorter than portion 176 of FIG. 7
because the exposure in FIG. 8 was longer and spanned more than one imaging frame
meaning fewer rows of detector elements were exposed to 100 percent of the
exposure prior to being read. Further, portion 224 of plot 204, corresponding to
regions 226 and 228 of respective imaging frames 200 and 202, includes row averages
that linearly decrease. Portions 214 and 224 of include lesser slopes than portions 168
and 188 of plot 159 in FIG. 7 due to the longer exposure in FIG. 8.
[0053] Due to the longer exposure extending two sampling periods, imaging
frames 198, 200, and 202 include image data indicated by cross-hatched regions 230,
232, and 234, respectively. As above, by determining the row average, the beginning
and ending of the exposure may be determined as well as the beginning and ending of
the imaging data.
[0054] To obtain the X-ray image all of the frames 150 including image data (e.g.,
frames 198, 200, and 202) are combined (i.e., added). To obtain the offset-corrected
X-ray image, the total number of frames 150 used to make the X-ray image (e.g.,
three, frames 198, 200, and 202) are multiplied time the calculated offset image (e.g.,
offset frame 194) and subtracted from the X-ray image.
[0055] Alternatively, the X-ray exposure may occur between readout periods.
FIG. 9 is a diagrammatical representation of sampling X-ray image data when the
exposure occurs after the end of one readout period but before the start of the next
readout. As above, FIG. 9 illustrates multiple frames 150 obtained from sampling the
matrix of detector elements. The frames 150 include offset frames 221 and 223 and
imaging frame 225. Offset frame 221 is acquired prior to the initiation of the
exposure. Offset frame 223 is acquired after the exposure ends and the frames 150
include no more image data. Neither of the offset frames 221 and 223 includes image
data. As in FIGS. 7 and 8, a row average is obtained for each frame in FIG. 9. Plot
227 from top to bottom indicates the row average of each row along the frames 150.
The row average in offset frame 221 is negligible since no exposure has occurred and
the detector elements remain fully charged. The beginning and ending of the
exposure is marked by lines 229 and 231, respectively. As illustrated, the exposure
occurred between readouts of the frames 221 and 225. Thus, portion 233 of plot 227
indicates all of the rows are exposed to 100 percent of the exposure prior to being
read. As a result, the image data indicated by cross-hatched region 235 is located
with a single frame 225 and there is no need to combine the imaging frame 225 with
any other frame. To obtain the offset-corrected X-ray image, the calculated offset
image (e.g., offset frame 221) is subtracted from the X-ray image (e.g., frame 225).
[0056] Increases in electronic noise may occur in combining sampled X-ray image
data from multiple frames (e.g., at least two imaging frames) to produce X-ray image
data capable of being reconstructed into a user-viewable image. For example,
assuming the X-ray image is obtained by combining three imaging frames with the
same offset, for a given pixel where Oij represents the offset value, the final value
of the pixel, p l . , is represented by the following formula:
Le mean and variance of the electronic noise are represented by
i j and E j p l j | , respectively, in the following formulas where
and
( + ) . (3)
Since, as shown above, the electronic noise has zero mean and the 4 values p , p !
p , and O. . are independent of each other, the electronic noise of the x-ray image
by combining N offset corrected images with the same offset becomes:
where s represents the standard deviation.
[0057] Another way of reducing the electronic noise is to use different offsets for
each of the imaging frames. In that case, the electronic noise of the final image
becomes:
[0058] A further way to reduce electronic noise is to use the averaged offset for the
reading frames. Assume that the offset is obtained by averaging M dark frames (i.e.,
offset frames). The noise of the offset is
and the noise of the combined image is
[0059] Equation (7) is less than equation (5) when M > N. Thus, when the number
of imaging frames combined are fewer (e.g., N=2) the averaged offset is preferred.
However, when the imaging frames combined are greater, then using the same offset
or separate offsets may be preferred.
[0060] FIG. 10 is a flow diagram of a method 236 for sampling and combining Xray
image data to produce X-ray image data capable of being reconstructed into a
user-viewable image that incorporates the techniques described above. The method
236 includes preparing the detector 22 (block 238). Preparation of the detector 22
may include beginning sampling data (e.g., offset data) prior to and independently of
initiation of an exposure. Following preparation of the detector 22, the method 236
includes performing an X-ray exposure via the X-ray radiation source 16 (block 240),
where the X-ray source is responsive to the source controller 54. After initiation of
the exposure, sampling of X-ray image data occurs via the detector 22 without a
priori knowledge of the beginning and ending times of the X-ray exposure (i.e.,
without communication of timing signals from the source controller 54) (block 242)
Indeed, sampling X-ray image data may occur during the X-ray exposure. The
method 236 further includes determining beginning and ending frames (e.g., imaging
frames) of the X-ray image data (block 244). The beginning and ending frames at
least span the duration in which the exposure occurred. As mentioned above, the
exposure may occur during a single imaging frame, but the X-ray image data may be
on multiple imaging frames. Thus, the beginning and ending frames may contain data
sampled during the duration in which the exposure occurred and data sampled outside
of the duration in which the exposure occurred. In particular, the beginning and
ending frames are determined by comparison of sampled data of at least the respective
and ending frames. As indicated above, the beginning and ending frames are
determined by identifying a changed in the sampled data values (e.g., row average)
indicative of exposure to X-ray radiation.
[0061] Yet further, the method 236 includes combining the sampled X-ray image
data of at least two imaging frames, where at least one of the frames spans the
duration in which the exposure occurred, to produce X-ray image data capable of
being reconstructed into a user-viewable image (block 246). As mentioned above, Xray
image data capable of being reconstructed into a user-viewable image may be
produced by generating offset corrected image data based upon data sampled from the
at least two imaging frames. For example, the offset corrected image data is
generated by combining sampled data prior to a beginning imaging frame with data
sampled from the at least two imaging frames as described above. Further, combining
the sampled X-ray image data of the at least two imaging frames includes selecting a
combination method based upon a noise parameter. In other words, as described
above, the calculation of the noise will depend on the number of imaging frames and
offset frames (i.e., offset frames) sampled prior to and during the occurrence of the
exposure to select the proper equation from those noted above to reduce electronic
noise when combining the sampled data from more than one frame.
[0062] The above techniques are illustrated in FIG. 11, a diagrammatical
representation of workflow during an acquisition sequence in which both image data
and offset data are acquired for producing user-viewable images. FIG. 11 includes an
acquisition sequence 248 of the detector 22 corresponding to the interaction between
the detector 22, portable detector control device 40, the operator or user 38, and the
X-ray source 16. The detector 22, device 40, and operation of the source 16 are as
described above. While the detector 22 is in idle mode, represented by region 250 of
the sequence 248, the operator 38 configures the source 16 as indicated by arrow 252.
Configuring the source 16 may include setting exposure parameters and the type of
exposure. Also, while the detector 22 remains in idle mode, the operator may position
the imaging subject and the source 16. Further, the operator 38 enters instructions
into device 40, as indicated by arrow 254, and sends instructions 256 to the detector
22 to prepare for exposure.
[0063] Upon receiving the instructions to prepare for acquisition of X-ray image
data, the detector 22 enters imaging power mode 258. The detector 22 begins by
scrubbing the panel, as indicated by region 260 of the acquisition sequence 248, to
equilibrate the circuitry on the panel. Then, the detector 22 reads one or more offset
frames from the panel (e.g., region 262), upon which the detector 22 sends a detector
ready signal 264 to the device 40. In one embodiment, the device 40 provides a visual
indication to indicate the ready state of the detector 22. In another embodiment, the
device 40 provides an audio indication. In a further embodiment, the device 40
provides both video and audio indications. In a yet further embodiment, the detector
22 provides a visual indication (e.g., flashing LED) to indicate the ready state of the
detector 22. In another embodiment, the detector 22 provides an audio indication. Yet
in another embodiment, the detector 22 provides both video and audio indications.
The operator 38 receives the ready signal on the device 40, as indicated by arrow 266.
Once the detector 22 is ready, the detector 22 begins continuously sampling or
reading frames as indicated by region 268 of the acquisition sequence 248 to detect an
exposure. At any time, the operator may initiate the exposure, as indicated by arrow
270, from the source 16. Upon initiation of the exposure, the detector 22 receives the
X-ray radiation 272 from the source 16. The detector 22 samples the frames to
determine the beginning and ending frames that span the exposure (e.g., frames 274
and 276). After termination of the exposure, the detector 22 may process the acquired
image data and send a preview of a reconstructed image, indicated by arrow 278, to
the device 40 for viewing by the operator 38. Alternatively, the data may be sent to
the device 40 for further processing and the generation of the reconstructed image.
After the exposure ends, the detector 22 reverts back to idle mode as indicated by
region 280 of the acquisition sequence 248.
[0064] As mentioned above, the detector 22 shifts from an idle mode to an
imaging power mode. In the imaging power mode, the detector 22 continuously reads
the panel, since the detector 22 lacks a priori knowledge (or data) of when the
exposure may occur. Thus, reading or sampling of data from the panel occurs during
the exposure. Transistors (e.g., FETs) of discrete picture elements then being sampled
are in a conducting state when the rows are enabled for readout. However, leakage
(e.g., FET leakage) may occur from those transistors of discrete picture elements not
then being sampled (i.e., transistors are in a non-conducting state when the rows are
not enabled for readout). Increasing the voltage (V0ff) to maintain the transistors not
then being sampled in a non-conductive state may reduce FET leakage. However,
reduction of the leakage may not persist if the transistors are biased for a while due to
bias age.
[0065] FIGS. 12 and 13 illustrate embodiments of techniques to overcome these
issues. FIG. 12 is a diagrammatical representation of an acquisition sequence 282 in
which different voltages are applied to reduce transistor leakage while sampling
image data, particularly during exposure. The acquisition signal 282 of FIG. 12 is the
same as acquisition signal 248 described in FIG. 11. The acquisition signal 282
includes regions 250 and 280 where the detector 22 maintains an idle mode. In
addition, the acquisition signal 282 includes regions where the detector 22 scrubs the
panel (e.g., region 260) and periods of sampling or reading the panel (e.g., regions
262 and 268). The detector 22 applies a first voltage 284 (e.g., less negativeV ff) to
the transistors of the discrete picture elements when the detector 22 maintains an idle
mode (e.g., regions 250 and 280). Thus, the detector 22 applies the first voltage 284
to the transistors of the discrete picture elements prior to receipt of X-ray radiation
(e.g., region 250). The detector 22 applies a second voltage 286 (e.g., more
negativeVoff) to the transistors of the discrete picture elements not then being sampled
when the detector 22 shifts to imaging power mode 258 (e.g., regions 260, 262, and
268) and begins sampling data from the discrete picture elements. In one
embodiment, the first voltage 284 may be applied, instead of the second voltage 286,
while scrubbing the panel (i.e., region 260). The application of the second voltage
286 to the transistors of the discrete picture elements not then being sampled also
occurs during receipt of X-ray radiation by the detector 22. Upon termination of
sampling X-ray data from the discrete picture elements (e.g., region 280), the detector
22 reapplies the first voltage 284 to the transistors of the discrete picture elements
after termination of the receipt of X-ray radiation by the detector 22.
[0066] The second voltage 286 is more negative than the first voltage 284. The
second voltage 286 may be at least approximately 1.3 times the first voltage 284. For
example, the first voltage 284 may be equal to or less negative than approximately - 11
volts. The second voltage 286 may be equal to or more negative than approximately -
15 volts. The first and second voltages 284 and 286 maintain the transistors in a nonconductive
state. By maintaining the second voltage 286 only during the imaging
power mode 258 and shifting to the first voltage 284 in idle mode (e.g., regions 250
and 280), the transistor leakage may be reduced while also avoiding bias age.
[0067] FIG. 13 is a flow diagram of a method 288 for sampling data from the
detector prior to and after an X-ray exposure while applying different voltages to
reduce transistor leakage. The method 288 includes applying the first voltage 284 to
transistors of the discrete picture elements (e.g., when detector 22 maintains idle
mode) (block 290). While preparing for the acquisition of X-ray image data, the
method 288 includes sampling data from the discrete picture elements while applying
the second voltage 286 to the transistors of the discrete picture elements not then
being sampled, where the second voltage 286 is more negative than the first voltage
284 (block 292). Upon sampling data while applying the second voltage 286, the
detector 22 may store sampled data prior to receipt of the X-ray radiation for use in
reconstruction of a user-viewable image from the X-ray image data (block 294).
Also, the method 288 includes receiving X-ray radiation on the detector 22 from the
X-ray source 16 (block 296). After exposure, sampling of X-ray image data from the
discrete picture elements occurs while applying the second voltage 286 to the
transistors of the discrete picture elements not then being sampled (block 298).
Sampling of data from the discrete picture elements also occurs during receipt of Xray
radiation, while applying the second voltage 286 to the transistors of the discrete
picture elements not then being sampled. After termination of receipt of X-ray
radiation, the detector 22 terminates sampling of X-ray image data from the discrete
picture elements (block 300) and re-applies the first voltage 284 to the transistors of
the discrete picture elements (block 302), for example, during the transition to idle
mode. As mentioned above, transistor leakage may be reduced while also avoiding
bias age by maintaining the second voltage 286 only during the imaging power mode
and shifting to the first voltage 284 in idle mode.
[0068] Technical effects of the embodiments include providing methods and
systems to allow for the retrofitting of conventional X-ray systems by replacing
cassettes with a digital X-ray detector. In retrofitting the X-ray systems, the digital Xray
detector does not communicate with the X-ray imaging system. Instead, the
detector communicates with a portable detector control device to receive instructions.
Since the detector does not communicate with the X-ray system, the detector lacks
data indicating the timing signals for an X-ray exposure. Thus, the detector in
preparation for and during an exposure may continuously read the panel of the
detector. The detector may include techniques to determine the beginning and ending
of the exposure and imaging data, gather and combine X-ray image data from
multiple frames, while reducing factors that may adversely affect the quality of the
image (e.g., electrical noise and transistor leakage).
[0069] This written description uses examples to disclose the invention, including
the best mode, and also to enable any person skilled in the art to practice the
invention, including making and using any devices or systems and performing any
incorporated methods. The patentable scope of the invention is defined by the claims,
and may include other examples that occur to those skilled in the art. Such other
examples are intended to be within the scope of the claims if they have structural
elements that do not differ from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from the literal languages
of the claims.
CLAIMS:
1. An X-ray imaging method, comprising:
performing an X-ray exposure via an X-ray radiation source responsive to a
source controller;
sampling X-ray image data via a digital detector without communication of
timing signals from the source controller;
combining the sampled X-ray image data of at least one imaging frame or two
or more imaging frames with at least one of the frames spanning a duration in which
the exposure occurred, to produce X-ray image data capable of being reconstructed
into a user-viewable image.
2. The method of claim 1, comprising generating an image frame where
the X-ray exposure occurs between image reading of two consecutive frames.
3. The method of claim 1, comprising determining beginning and ending
frames that span at least the duration in which the exposure occurred.
4. The method of claim 3, wherein each of the beginning and ending
frames contain data sampled during the duration in which the exposure occurred and
data sampled outside of the duration in which the exposure occurred.
5. The method of claim 3, wherein the beginning and ending frames are
determined by comparison of sampled data of at least the respective beginning and
ending frames.
6. The method of claim 5, wherein the beginning and ending frames are
determined by identifying a change in sampled data values indicative of exposure to
X-ray radiation.
7. The method of claim 1, comprising preparing the detector by sampling
data prior to the exposure.
8. The method of claim 7, wherein preparing the detector comprises
beginning sampling of detector data prior to and independently of initiation of the
exposure.
9. The method of claim 1, comprising producing X-ray image data
capable of being reconstructed into a user-viewable image by generating offset
corrected image data based upon data sampled from the at least one imaging frame.
10. The method of claim 9, wherein the offset corrected image data is
generated by combining sampled data prior to a beginning image frame with data
sampled from the at least one imaging frames.
11. The method of claim 1, wherein combining the sampled X-ray image
data of the two or more imaging frames comprises selecting a combination method
based upon a noise parameter.
12. The method of claim 11, wherein the noise parameter is based upon a
number of imaging frames that at least span the duration in which the exposure
occurred, and a number of imaging frames sampled prior to initiation of the exposure.
13. An X-ray imaging method, comprising:
performing an X-ray exposure via an X-ray radiation source;
sampling X-ray image data via a digital detector without apriori knowledge
of beginning and ending times of the X-ray exposure;
determining beginning and ending frames of the X-ray image data; and
combining the sampled X-ray image data of at least one imaging frame or two
or more imaging frames with at least one of the frames spanning a duration in which
the exposure occurred, to produce X-ray image data capable of being reconstructed
into a user-viewable image.
14. The method of claim 13, comprising sampling X-ray image data during
the X-ray exposure.
15. The method of claim 13, wherein the beginning and ending frames
contain data sampled during the duration in which the exposure occurred and data
sampled outside of the duration in which the exposure occurred.
16. The method of claim 13, wherein the beginning and ending frames are
determined by comparison of sampled data of at least the respective beginning and
ending frames.
17. The method of claim 16, wherein the beginning and ending frames are
determined by identifying a change in sampled data values indicative of exposure to
X-ray radiation.
18. The method of claim 13, comprising preparing the detector by
sampling data prior to the exposure.
19. The method of claim 18, wherein preparing the detector comprises
beginning sampling of detector data prior to and independently of initiation of the
exposure.
20. The method of claim 13, comprising producing X-ray image data
capable of being reconstructed into a user-viewable image by generating offset
corrected image data based upon data sampled from the at least one imaging frame.
2 1. The method of claim 20, wherein the offset corrected image data is
generated by combining sampled data prior to the beginning image frame with data
sampled from the at least one imaging frame.
22. The method of claim 13, wherein combining the sampled X-ray image
data of the two or more imaging frames comprises selecting a combination method
based upon a noise parameter.
23. The method of claim 22, wherein the noise parameter is based upon a
number of imaging frames that at least span the duration in which the exposure
occurred, and a number of imaging frames sampled prior to initiation of the exposure.
24. An X-ray imaging system comprising:
an X-ray radiation source;
a source controller coupled to the source and configured to command X-ray
emission of X-rays for image exposures;
a digital X-ray detector configured to sample X-ray image data without
communication from the source controller; and
a portable detector control device configured to communicate instructions to
the detector for acquisition of the X-ray image data and to receive the X-ray image
data from the detector for processing, image reconstruction, and image preview;
wherein at least one of the detector, the portable detector control device, and a
processing system in communication with the detector and/or the portable detector
control device is configured to combine the sampled X-ray image data of at least one
imaging frame or two or more imaging frames with at least one of the frames
spanning a duration in which the exposure occurred, to produce X-ray image data
capable of being reconstructed into a user-viewable image.
25. The system of claim 24, wherein producing X-ray image data capable
of being reconstructed into a user-viewable image by generating offset corrected
image data based upon data sampled from the at least one imaging frame.
26. The system of claim 25, wherein the offset corrected image data is
generated by combining sampled data prior to a beginning frame with data sampled
from the at least one imaging frame.
27. A digital X-ray detector comprising:
circuitry configured to sample X-ray image data without communication from
timing signals from a source controller, wherein the source controller is configured to
command X-ray emissions of X-ray from an X-ray radiation source for image
exposures, and to combine the sampled data of at least one imaging frame with at
least one of the frames spanning a duration in which an X-ray exposure occurred to
produce X-ray image data capable of being reconstructed into a user-viewable image.
28. The digital X-ray detector of claim 27, wherein the circuitry is
configured to combine the sampled data of two or more imaging frames with at least
one of the frames spanning a duration in which the exposure occurred to produce Xray
image data capable of being recontructed into a user-viewable image.
29. The digital X-ray detector of claim 27, wherein the circuitry is
configured to generate an image frame where the X-ray exposure occurs between
image reading of two consecutive frames.
30. The digital X-ray detector of claim 27, wherein the circuitry is
configured to determine beginning and ending frames that span at least the duration in
which the exposure occurred.
31. The digital X-ray detector of claim 30, wherein each of the beginning
and ending frames contain data sampled during the duration in which the exposure
occurred and data sampled outside the duration in which the exposure occurred.
32. The digital X-ray detector of claim 30, wherein the circuitry is
configured to determine the beginning and ending frames by comparing sampled data
of at least the respective beginning and ending frames.
33. The digital X-ray detector of claim 32, wherein the circuitry is
configured to determine the beginning and ending frames by indentifying a change in
the sampled data values indicative of exposure to X-ray radiation.
34. The digital X-ray detector of claim 27, wherein the circuitry is
configured to prepare the detector by sampling data prior to the exposure.
35. The digital X-ray detector of claim 35, wherein the circuitry is
configured to begin sampling of detector data prior and independently of initiation of
the exposure.
36. The digital X-ray detector of claim 27, wherein the circuitry is
configured to produce X-ray image data capable of being reconstructed into a userviewable
image by generating offset corrected image data based upon data sampled
from the at last one imaging frame.
37. The digtial X-ray dector of claim 36, wherein the offset corrected
image data is generated by combining sampled data prior to a beginning image frame
with data sampled from the at least one imaging frame.
38. The digital X-ray detector of claim 28, wherein combining the sampled
X-ray image data of the two or more imaging frames comprises selecting a
combination method based upon a noise parameter.
39. The digital X-ray detector of claim 38, wherein the noise paramater is
based upon a number of imaging frames that at least span the duration in which the
exposure occurred, and a number of imaging frames sampled prior to initiation of the
exposure.