Imaging system and method

Abstract

The present invention relates to an imaging system for imaging specimen, such as in medical scanning, with a possibility of the specimen being of any kind of nature including organic and inorganic bodies, compositions and parts. The invention is applicable to a wide variety of applications, hence may amongst others further relate to airport security scanners, monitoring flow of liquids, e.g. like oil or mud, and (quality) control of goods.

Description

[0001] IMAGING SYSTEM AND METHOD

[0002] The present invention relates to an imaging system for imaging specimen, such as in medical scanning, with a possibility of the specimen being of any kind of nature including organic and inorganic bodies, compositions and parts. The invention is applicable to a wide variety of applications, hence may amongst others further relate to airport security scanners, monitoring flow of liquids, e.g. like oil or mud, and (quality) control of goods.

[0003] BACKGROUND OF THE INVENTION

[0004] Known scanning methods and devices, methods for manufacturing the same and methods or principles of design are generally known, both in the form of the widely known type of scanners such as so-called MRI scanners and from the less widely known advancements relative thereto such as e.g. made public by international patent publication WO2020141435. The latter design uses X-ray pulses directed towards a scintillator for acquiring optical images in conjunction with a timed shutter device. Advancements in research within this field may also be known from publications like 'Advancements in Transmitters and Sensors for Biological Tissue Imaging in Magnetic Induction Tomography in Sensors' 2012, 12, 7126-7156; doi:10.3390 / s120607126, and in 'A magnetic induction tomography system for samples with conductivities below 10 S m-1' in Meas. Sci. Technol. 19 (2008) 045501 (11 pp), which latter provides an example of a setup with coils and measuring matter in between. An advantage of this technology is that it maintains an advantage of absence of galvanic coupling between the device and the object to be imaged. Researcher Dugo Gursoy in this respect, in his 2011 article ' Enhancing Impedance Imaging Through Multimodal Tomography' proposes a concept of this technology in which an oscillating primary, generated by an excitation coil with a conductive medium under investigation. A sensor side of this concept senses the field caused hereby as well as a secondary field of eddy currents induced in the medium during primary field propagation and penetration therein.

[0005] Yet, in general, and despite previous advancements in magnetic induction tomography, the current technology for scanning of organic bodies, in particular human bodies, but also for cargo, is based on large machines that sometimes have a high energy load due to radiation of e.g. X-ray, used for generating attenuation contrast images of material of interest, for which special pre-cautions are taken in order to mitigate danger and / or harmful influence. In this respect also MRI typically is often categorized similar to other medical imaging techniques such as PET, as big, i.e, voluminous systems, applying intrinsically dangerous and complicated to use techniques. These traditional imaging techniques therefor require highly skilled operators. One consequence of the latter, apart from costs, is that also this requirement is a limiting factor to growth in the sector of human and non-human body or object scanning. Also, very expensive technology is most often still used in practice, such as large magnets cooled to liquid Helium temperatures, or alternatively use radiation type technologies such as ultrasound that lack the resolution for precise diagnostics, either in goods or in human tissue. Hence while it is evident that scanning technology has advanced over recent decades, it suffers the draw back to allow only limited access to the public. It may further suffer from one or more of additional downsides including initial or instalment costs, operating costs, volume, complexity, potential hazard, and the requirement of professional personnel for operating the scanning equipment. Where it is attempted to overcome such draw backs, such as in magnetic induction tomography (MIT), signal to noise ratio or SN at the receiver side appears to problematic.

[0006] It is remarked that in order to gain resolution, CT-scanning needs to minimize the size of the source, since a larger source causes some blurring, which needs to be reduced computationally. In the present invention, a relatively large amount of sources is used, which is not, at least not very well possible at a CT-scanning concept, since X-rays eventually are harmful in relation to bodily tissue.

[0007] It is an object of the present invention to arrive at an improved imaging system, overcoming certain if not a good deal of draw backs of the known scanner technology.

[0008] BRIEF DESCRIPTION OF THE INVENTION

[0009] The present invention relates to an imaging system for imaging an object such as a human or nonhuman body using imaging signals with a frequency between 1 MHz and 500 MHz according to claim 1.

[0010] The imaging device comprises a plurality, e.g. more than 10, emitter devices wherein each emitter device comprises an emitter antenna which is configured for emitting a corresponding imaging signal, for example an electromagnetic imaging signal, to the specimen. The emitter antennas have a send area that is electrically small compared to the imaging signal. The electromagnetic imaging signal may have a frequency between 1 MHz and 500 MHz. The emitter devices may be arranged in an distributed around a imaging space, e.g. a doorway or a bed, wherein each antenna is aimed at the imaging space for sending the corresponding imaging signal to a specimen in the imaging space. Each emitter antenna has an effective send area, e.g. the area of the antenna that effectively emits the imaging signal to the imaging space, with a dimension smaller than 10 mm.

[0011] Each emitter device further comprises a corresponding current burst generator which is connected to the corresponding emitter antenna for providing a current burst to the corresponding emitter antenna for causing the corresponding antenna to emit the corresponding imaging signal. Thus, each emitter device has a dedicated, and preferably local, current burst generator connected to the antenna for providing a current to the antenna for providing the imaging signal. In embodiments, the antenna is provided within 200mm of the corresponding current burst generator. Each current burst has a burst peak above 50V and a burst width below 1 ms in the emitter antenna.

[0012] The imaging system further comprises a plurality of receiver devices with receiver antennas for receiving a transmission signal from the specimen, wherein the transmission signal is caused by a transmission of an imaging signal by the specimen. Preferably, the receiver antennas have a receiver area that is electrically small compared to the imaging signal. The receivers may also be arranged around the imaging space. For example, the receivers and emitter devices may be provided alternatingly around the imaging space. The receivers and emitter devices may be provided opposite each other, for example all emitters devices at one side and all receivers at the other side. Other configurations are also possible. The receivers antennas are configured to receive a signal from the specimen which signal is a result of a transmission of the imaging signal by the specimen. Thus, the received signal depends on the send imaging signal and on the specimen. Knowledge of the imaging signal and the received signal may be used to determine a characteristic of the specimen. Furthermore, the receiver antennas may be configured to receive the imaging signal directly, e.g. to allow to measure an empty imaging space and / or to calibrate the imaging system.

[0013] Each current burst generator comprises an electrical circuit operatively connected to the corresponding antenna at an antenna connection location of the electrical circuit, wherein the electrical circuit comprises a MOSFET switch with an internal capacitance below 5 nF, a capacitor having a capacitance between 1 nF and 1 mF, and an inductor with an inductance between 50 nH and 1000 nH, wherein the antenna connection location is between the MOSFET switch and the inductor in the electrical circuit. The electrical circuit, in particular the MOSFET switch in combination with the inductor, of the invention allows to generate the current burst required to send the imaging signal having a frequency between 1 and 500 MHz. The electrical circuit is connected to a power source for charging the capacitance.

[0014] The imaging system further comprises a processor connected to the plurality of emitter devices for causing the corresponding current burst generators to provide the current burst causing the emitter antennas to emit the imaging signal and which is connected to the plurality of receiver devices so that the processor is configured to obtain, for each emitted imaging signal, a corresponding transmission signal representative of a transmission of the imaging signal through the imaging space and received by the receiver device. The current burst is provided to the associated antenna by causing the corresponding MOSFET switch to switch between an open and closed configuration with a frequency between 1 kHz and 100MHz. wherein the imaging system, e.g. the processor thereof, is configured to: consecutively cause each current burst generator to provide a current burst to the associated emitter antenna by: o charging the capacitor with the power source; o providing a switching signal between 0.1 MHz and 100 MHz to a gate of the MOSFET switch causing the MOSFET switch to switch from an open configuration to a closed configuration and back to the open configuration thereof generating the current burst with a burst peak above 50 V and a burst width below 1 ms and discharging the capacitor; consecutively emit, by the emitter antenna receiving the current burst, an imaging signal with a frequency between 1 MHz and 500 MHz, i.e. which emitting of the imaging signal is caused by the current burst; determine an image of the specimen in the imaging space based on a comparison of the received transmission signals to one or more calibration signals, e.g. obtained by performing a measurement of an imaging space without specimen therein.

[0015] In embodiments, the time between consecutive imaging signals may be lower than 1 ms.

[0016] The plurality of receiver devices are configured to provide to the processor, for each emitted imaging signal, a corresponding transmission signal representative for a transmission of the imaging signal through the imaging space and received by the associated receiver device. In practice, a single emitted signal emitted by one of the plurality of antennas may cause a transmission signal that is received by multiple, e.g. all, of the antennas and provided to the processor. Thus, from a single emitted signal, many received signals may be obtained.

[0017] The processor is configured to determine an image of the specimen based on the received transmission signals. For example, the image may be determined based on a comparison of received transmission signals when a specimen is in the imaging space and received transmission signals when no specimen is in the imaging space.

[0018] A time between two imaging signals sent by two consecutive emitter devices may be below 1 ms. This allows to have a time between a start of a previous current burst and a start of a present current burst to be below 2ms, since the burst width of the current burst is below 1 ms.

[0019] Each emitter device may be activated in turn by the processor such that each emitter device emits an imaging signal such that the receiver devices may receive a transmission signal caused by transmission of a single imaging signal. The current burst having a burst peak above 50 V and a burst width below 1 ms allows the emitter device to emit the imaging signal.

[0020] Thus, the imaging system allows for a new and inventive imaging technique of a specimen. The energy load of the imaging system may be relatively low due to the current burst having a burst peak above 50V and a burst width below 1 ms. Furthermore, the imaging system may be integrated, e.g. in a doorpost or hallway, allowing imaging of a human passing therethrough. For example, the imaging system may be integrated in doorpost in a household.

[0021] The invention further allows for a medical scanner that is relatively small while having a relatively high resolution and a low signal to noise ratio. By consecutively sending burst to each of the antennas information received by the antennas when a burst is emitted allows to create an image matrix based on the knowledge of which of the antennas emitted the signal. The signal to noise ratio is kept relatively small by the use of an ultra large signal. In embodiments, each emitter device and an associated receiver device are embodied as an emitterreceiver device, e.g. wherein, each emitter-receiver device comprises a single antenna for emitting imaging signals and receiving transmission signals.

[0022] In embodiments, each emitter antenna is electrically small, i.e. has a largest dimension of the effective send area smaller than 1 / 10th, preferably 1 / 50th, more preferably 1 / 100th, a wavelength of an emitted imaging signal.

[0023] In embodiments, the effective send area of the antennas comprises conductive wires that are printed on a print surface.

[0024] In embodiments, the antennas comprise an input wire which is at a first end thereof connected to the effective send area, e.g. and which is connected at another end thereof to the antenna connection location, and wherein the antennas comprise a termination wire which is at a first end thereof connected to the effective send area at a location opposite to the associated input wire.

[0025] In embodiments, the input wire has a length of between 50mm and 200mm and / or the termination wire has a length between 5mm and 15mm.

[0026] In embodiments, the emitter devices and receiver devices are provided moveably around the imaging space and wherein the imaging device is configured to move the emitter devices and / or the receiver devices between emitting and / or receiving signals.

[0027] In embodiments, the imaging system comprises more than 10 emitter devices and more than 10 receiver devices.

[0028] It is in respect of the present invention further remarked, that while generating signal by the current burst having a burst peak above 50V and a burst width below 1 ms, it may be regarded as to be relatively simple to do in practice, it is not trivial to come up with. In this respect it should be noticed that many of the parts in field of scanning or imaging, e.g. as in MIT, and as used for effecting the present invention in practice, is rated less than 1 Watt to generate pulses. Yet a peak in signal as preferred according to the embodiment, may be well over 1000 Volt and over l OOOAmps, hence over 1 Mega Watt equivalent. Apart from such requirement to the order of magnitude of the signal, the embodiment further recognized that the nature of the signal is further to be set by utilizing ultimately small duration thereof, i.e. for a fraction of a second. It might hence perhaps be worded as to cause a flashing pulse as it were, not to be confused with continuous signal, sometimes denoted pulsated sine wave, as may be encountered in existing scanning systems and concepts. While the rating of ordinary, and if at all available in this form, even dedicated components generally prevents, at least discourages the use of electric components at the newly developed load levels, survivability of the components, or entire equipment even, is also to the skilled person in this field, a matter of discouraging concern.

[0029] In embodiments, for each emitter device, an effective resistance of the electrical circuit may be less than 1 k Ohm. It was found experimentally that these values allow for an oscillating current burst in the emitter device.

[0030] In embodiments, the antenna of each emitter device may be embodied as a monopole antenna having an elongated send area having a first dimension between 5mm and 15mm and a second dimension between 0.5mm and 2mm. In embodiments, the effective send area is smaller than 20mm x 20mm, in further embodiments the effective send area is smaller than 10mm x 10mm.

[0031] The invention further relates to a method for imaging a specimen wherein use is made of an imaging system according to the invention.

[0032] In embodiments, the method comprises: consecutively causing each current burst generator to provide a current burst to the associated emitter antenna by: o charging the capacitor with the power source; o providing a switching signal between 0.1 MHz and 100 MHz to a gate of the MOSFET switch causing the MOSFET switch to switch from an open configuration to a closed configuration and back to the open configuration thereof generating the current burst with a burst peak above 50 V and a burst width below 1 ms and discharging the capacitor; consecutively emitting, by the emitter antenna receiving the current burst, an imaging signal with a frequency between 1 MHz and 500 MHz, i.e. which emitting of the imaging signal is caused by the current burst; determining an image of the specimen in the imaging space based on a comparison of the received transmission signals to one or more calibration signals, e.g. obtained by performing a measurement of an imaging space without specimen therein.

[0033] BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Various aspects of the invention and an example of a possible embodiment of the invention are illustrated in the drawings in which:

[0035] FIG. 1 A in a block diagram provides a typical set up for a prior art tomography system tissue imaging, here represented by way of a magnetic induction tomography system; FIG. 1 B provides field line diagram for various types of conventional electro-magnetic imaging e.g. as by FIG. 1 , providing a schematic signal view from excitation to indirect detection via a to be investigated object, exposed to applied or induced current;

[0036] FIG. 2A and FIG. 2B represent a field line diagram as in FIG. 1 B, now related to an embodiment of the invention, with FIG 2B instead of one, depicting an embodiment with a number of antennas;

[0037] FIG. 3A-3B a variant of a schematic and conceptual representation of an effective electrical circuit for an emitter device;

[0038] FIG. 4 is a representation of a switch generated trigger signal as used by the present invention for activating a capacitor in an electrical circuit of an emitter device according to the present invention, for example with the interval between the consecutive trigger signals being larger than a current burst width;

[0039] FIG. 5, by a squared separated current burst schematically depicts a variation in generated electromagnetic field caused by a switching of the MOSFET switch;

[0040] FIG. 6A to 6C represent various possible configurations of a imaging device or portal thereof for the pulsed imaging concept of this invention, with respectively a standing version, a walk through version and a revolving version;

[0041] FIG. 7 is a partial close-up representation of a possible, so called flashing device of the imaging device;

[0042] FIG. 8 schematically depicts the nature and typically possible manner of an application use of a device in accordance with the present invention, here in conjunction with a port like carrier; FIG. 9 shows a depiction of an electrical circuit which may be used in an emitter device of the imaging device;

[0043] FIG 10 shows a depiction of another electrical circuit which may be used in an emitter device of the imaging device; and

[0044] FIG 11 shows a depiction of an emitter antenna and / or a receiver antenna.

[0045] The invention will along with the above indicated set of figures, in the following by way of example be described in more detail.

[0046] FIG. 1 is a block diagram, developed by Binns et al, of a typical set up for magnetic induction tomography system as described in publication “Imaging molten steel flow process”. Meas. Sci. Technol. 2001 , 12, 1132-1138. The diagram generically applies for set ups in Magnetic Induction Tomography, hence forth MIT, hence also applies for other applications of this technology such as biological tissue imaging as in plant, animal and human bodies. This known technology departs from a basic principle of generating a current density distribution inside a body and recording the resultant electric fields. The system conceptually comprises an scanning device 1 , with a sensor array 2, controlled by conditioning or control electronics 3 and a host computing device 4, realising useful output 5, here in the form of a matrix, as may be based on executing a reconstruction algorithm on measured data. The computing device may be in the form of a host computer, performing all of the functions of outputting control signals to the scanning device, generally by outputting a control signal to the conditioning electronics 3, receiving measured data and performing an output, or information generating algorithm on the received detector data. The computing device is here connected to the control electronics 3 via electronics control conduit 10 comprising control signal output lines and data input lines to the computing device. Similarly the conditioning electronics 3 is connected the scanning device 1 , via sensor control conduit 9, comprising both a field control signal output line and a measured signal line. The sensor array of the imaging device of the typical MIT system of figure 1 further comprises excitation coils 6 generating a magnetic field 8, and detection coils or sensors 7. FIG. 2 in the latter respect illustrates the operation of a primary electro-magnetic field as generated by the antenna (for instance a wire or a coil) 6, a field of currents induced by the object and a receiver coil 7 thereof, alternatively denoted detection coil and sensor.

[0047] In embodiments, the present invention may realize an unusually large but short lived primary electromagnetic field, that the reduction in strength thereof as a consequence to exposure of a specimen, is still of such enormously larger magnitude than conventionally encountered, that the S / N ratio of such a strength reduced primary electro-magnetic field still realizes the significantly improved S / N signal as desired at a field receiver side.

[0048] Such electro-magnetic field strengths of the imaging signal as achieved by the present invention may be provided using an electrical circuit according to the invention.

[0049] The imaging system may provide an image based on, e.g. variation of the magnetic field as measured in areas of the body or object in comparison with a recorded emission of field, e.g. with a known time or moment of emission. The present invention may measure change in received electro-magnetic field as a consequence of the presence of a specimen in the imaging space between the emitter devices and receiver devices. This may then be compared to a measured electro-magnetic field obtained during a calibration when no specimen was present in the imaging space. Hence the nature of the specimen may strongly determine the transmission received.

[0050] In respect of this new concept and invention, Figures 6 to 8, schematically depict a nature and possible manner of use of the imaging system and concept designed in accordance with the present invention. In figures 3 to 8, some embodiments of the imaging system are shown. The plurality of emitter devices and receiver devices of the imaging device 2, may in one potential form and nature according to the present invention in principle ultimately be comparable to that of so called LED-strips as illustrated by FIG.7 and / or comprise antennas as shown in FIG. 11.

[0051] In an embodiment, the imaging device 2 comprises a plurality of emitter devices and receiver devices, incorporated in panels that may be up to typically 10cm of depth. The invention includes the fabrication or embodiment using an array, build-up of a holder or so-called support carrying a large amount of PCBs where one PCB holds a single or a limited subset of emitter- and / or receive devices. Such setup reflects a desirable embodiment of the presently invented imaging system, in that the current burst generator, rather than conventionally being incorporated in a separate driving electronic circuitry module, is in the present invention typically included locally, i.e. close to an antenna, in an emitter device such that a system according to the present invention comprises a plurality of current burst generators. Reason for such preference in set-up is that the currents as generated by the capacitor may be of such magnitude that the feed line to an antenna even the short lived outburst of the present invention, is to maintained short as possible. Hence most preferably each emitter is locally provided with an LCR circuit, although in principle a setup with an RLC circuit feeding a limited number of antennas may be conceivable under careful design.

[0052] It may be evident that with the local design, the need for amplification circuits is obviated. For as far as an amplifier would notwithstanding be applied as part of the system, it would typically be with selectable gain. It will further be clear from the preceding that the voltage supply HV as also indicated in e.g. FIG’s. 5 for such local circuits may and is preferably maintained as a central component.

[0053] The emitter devices of the invention may according to another independent aspect thereof be designed to be applied in conjunction with a base element 18, here port like shaped, such as in a door post as in FIG. 8 or a door-like configuration with two, supporting side panels defining a imaging space as in FIG.’s 6A to 6C. In the latter respect FIG. 6A represents a stationary set-up, potentially providing the feature of and use as a walk through device as illustrated by FIG. 6B, while FIG. 6C illustrates an embodiment with revolving panels with the specimen standing still. The nature of the imaging device of the invention either or not in conjunction with a provided scanner base 18, allows it to be easily applied for many applications, both in medical environments and in other environments, in particular including a domestic one. The emitter device of the invention is in the here depicted example embodiment of FIG. 8 provided with a flexible carrier strip 17 for supporting a system of connected emitter antennas 6, and receiver antennas 7. The new imaging device 2 connects to control electronics via wiring such as pulse or feeding line 12 and resulting, i.e. detected signal line 13. The system comprises otherwise nondepicted control electronics, e.g. positioned in a small cabinet in the vicinity of the scanner device, which in turn may be controlled by a remote processor, e.g. by wireless transmission.

[0054] While the embodiments of figure 6, the so-called “walk through-” imaging device of FIG. 6B sets forth a possibility of the present technology, other more conventional geometries are still possible and in some circumstances or instances such as early stages of this technology possibly to be preferred. In a perhaps most readily to be realized embodiment, the invention would, as in FIG. 6A, also be in the form of a revolving portal, or a generally portal shape in case of two panels, however would require the subject or body to stand still for a brief period of time. Such a stationary portal could, with the present invention be made to form a part of everyday life routine, for instance in the form of two panels mounted in a shower or bathroom. The present invention in fact allows for many type of embodiments and forms of use. It could for instance be made part of a chair and desk so that one could get scanned while the person is in sitting position, either purposely or at home or during routine situations such as at work and in case of car driving. In a third main modality of embodying and using the present new technology, represented in FIG. 6C, the new imaging system may be arranged with moving parts, analogous to a known, so-called CT scanner. As the requirements for an imaging system based on the present new technology are such that a scan can be made anywhere, every imaginable implementation is possible as long as the object, person or body under investigation is part of, or otherwise stated, between an emitter and a related receive array.

[0055] Figure 9 shows an electrical circuit of an emitter device for creating an current burst by switching the MOSFET switch between the open configuration and closed configuration. It was found that an oscillating signal is created in the circuit which allows the emitter to emit a desired signal.

[0056] Figure 10 shows another electrical circuit of an emitter device for creating the oscillating current burst by switching the MOSFET switch between the open configuration and the closed configuration. The MOSFET switch of the circuit shown in figure 11 may have a voltage rating greater than 100V, a low internal capacitance below 5 nF and / or a gate resistance below 10 Ohm. The low internal capacitance of the MOSFET switch was found to result in an oscillation frequency between 1 MHz and 500MHz such that biological tissue may be made visible.

[0057] The C1 capacitance may be charged by the (DC) power supply V1 and serves as a charge buffer for starting the oscillations. It was found that the charging voltage of the capacitor influences a peak voltage of the current burst only indirectly. It was found that the frequency and amplitude of the imaging signal depends in large part on the L4 inductor and the MOSFET switch, wherein the appropriate signals are generated when use is made of the MOSFET switch and inductor as described herein.

[0058] Currents well above 1A and voltages of well above 100V may be achieved with the electrical circuit according to the invention resulting in a peak power of 100W and up. For comparison, for a 50 ohm matched antenna system capable of achieving 350V, a current of 7A may be needed in a local signal generator of at least 2 kW. Such systems are large and bulky. See for example EuroCaster DDS 2000 Digital FM Transmitter 2 kW, 3U, Stereo, Soft clipper, Web, SNMP remote, 7 / 16 con - EuroCaster FM Transmitters - BroadcastStoreEurope.com. This means operation of a sufficient number of send units for creation of a high resolution image (typically >100 for a human) connected with low enough impedance to the setup impossible.

[0059] The invention may use a setup with a MOSFET, and a 500nH coil and 0.1 uF capacitance which creates a 350V peak with 6A current = 2.1 kW peak power. A 20V sine (similar pulse shapes such as square pulse triangle or similar could also be used) with a base frequency of few MHz may be applied to the gate of the MOSFET switch to generate the current burst.

[0060] Extremely low power may be lost during a current burst, the charge initially present in C1 moves back and forth through the circuit but as the pulse is mainly generated in the off state of the MOSFET the charge doesn’t drain to ground meaning generation of a pulse doesn’t significantly reduce the charge present on C1 after a single pulse was created. This reduces the need for large (lumpy) power supply, capacitance charge banks and similar equipment to create the same properties as we have in a pulse. The antenna connection location is indicated in Figure 10 by ant such that the imaging signal is sufficient to allow imaging of the specimen.

[0061] Figure 11 shows an example of an antenna. The antenna may be smaller than 100mm to have a desired spreading of the point spread function. The shape of the antenna as shown in the figure allows to improve the imaging signal. The tip of the antenna which is bend parallel to the connection to the circuit has a reduced signal strength compared to the send area which is formed by the central (base) part of the U-shape. The send area may be formed by multiple parallel thin wires, e.g. with a diameter smaller than 1 mm, to increase the send efficiency.

[0062] The technique allows an imaging signal in accordance with the present invention in which different frequencies are used, typically ranging from 1 MHz up to 500 MHz.

[0063] In application of the present invention, different imaging signals may use different frequencies, which frequencies are absorbed differently by the specimen under investigation, e.g. human or any other organic or in-organic specimen. In this respect it is not just about simple absorption, i.e. reduction in amplitude of a signal but also in phase of the signal and deformation from original shape. For instance a 100MHz block wave, generally represented by FIG. 5 with block shaped signal Pb, superimposed on e.g. a one (1) us pulse would no longer be an exact block wave at the point of detection which provides information additional to the reduction of the absolute magnitude of the block wave. Hence the invention, in addition to variation in electro-magnetic field strength also detects and analyses, i.e. derives information from signals superimposed on the imaging signal.

[0064] By using the imaging system, data is obtained with which a reconstruction of the specimen under investigation can be made resulting in a three dimensional image of the specimen. In such a configuration one emitter device may be active, i.e. produce an imaging signal, at any given time, while typically a large number if not all of the receiver devices be set active in the system in detecting each transmitted imaging signal.

[0065] An insight underlying the present invention is that within the system according to the invention, sufficiently high power density as required for imaging may be achieved by generating a short current burst, in some embodiments an ultra-short current burst, while creating very high power density. Such burst duration could typically be between 10 ns and 1 ms for a human specimen, but may also depend on the carrier frequencies needed for the type of specimen. In principle the range up to 1 second may be utilized, however may for the purpose of using common electrical components in normal life expectancy, preferably remain in the order of up to tens of milliseconds. The invention recognizes that if such burst is generated for a short enough period of time, standard control or scanner components will not be caused to fail, either instantly or over time.

[0066] After one imaging signal is transmitted the imaging device switches to the next emitter device allowing the imaging devices to be used sequentially thus generating a constant string of imaging signals for measurement without damaging an emitter device. Such a sequence may be looped for a very large number of times, e.g. up to 1000 times or more, in order to generate sufficient resolution in the image to be generated from the transmission signals. It was further recognized as an interesting advantage of the idea underlying the present invention, that at using pulsed signals at least the timing and in principle also the shape of the pulse generated are precisely known, which feature or features may be used for easier detection and-or identification of its resulting signal.

[0067] A main advantage of the presently proposed design over existing imaging techniques is that the technique of this invention does not use intrinsically expensive technologies, nor potentially harmful technologies such as X-ray and radioactive contrast. Another highly relevant advantage is that it does not require specially trained operators to function. Last but not least it has, certainly in mass production, the potential to become economically available for use to a large, non-specialized public. The proposed technology is also in size comparatively very compact, increasing the potential installation options to inside a door frame or hallway or similar.

[0068] In earlier research on MIT the frequency and the amplitude of the signal is embodies as continuous sinusoidal signal, results in a relatively very low signal to noise ratio on the receiver side. Follow up research was there focused on enhancing the sensitivity of the receiver. An advantage of the present invention in this respect is that it rather uses a very high amplitude signal in a very short period of time, i.e. a separated current burst, so as to dramatically increase the signal to noise ratio while keeping the total energy in the system, a factor of energy overtime including the off time in between pulses, low, resulting in currents that are very high, and providing the advantage of favorably causing very large electro-magnetic (EM) field, yet acceptable for reason that it exist in only a very short period of time.

[0069] The result as well as the characterizing specifications of use of the method according to this invention are however spectacular. Where report on earlier research shows that an EM signal can be used to detect a specimen but, it also assessed that the issues of image resolution, signal-to-noise ratio and measurement speed had not been resolved. In contrast the present invention may resolve some or all of these issues by the change towards using a signal typically composed of separated current bursts, rather than a continuous but amplified current. The invention thereby enables much smaller sized and thus a high density of send and receive units 6 and 7, in turn rendering in fact unprecedented high imaging resolution.

[0070] In application of the new method and device of scanning, new forms of application, which may in principle be subject of independent claims, of imaging come into perspective. The invention hence further holds applications like early diagnose, or signaling I measuring for early indication that visit or opinion of a physician may be required. This could e.g. include to collect data from people in their healthy state on a daily basis, creating a large and very extensive understanding of the healthy situation of each person that owns a scanner. By placing the scanner at home and creating this data the difference with the normal, healthy situation, results in a very early diagnose of “abnormalities”. The very early diagnose makes less invasive treatments possible. Typically such diagnose is not medical. Rather it is a diagnosis of occurring changes of the body. The personal data combined with the “alluser” data, and recorded future illnesses of any of the users, results in a steep learning curve and more precise diagnosis. When a user describes the diagnose from a doctor the past data will be rerun with the diagnosis looking for clues to detect the illness. That knowledge is than used on all user-data I images. This combination increases the learning curve of the diagnosis extremely and makes precise diagnostics and early diagnostics possible.

[0071] The present invention, apart from what has been described in the above, also relates to all details in the figures, at least for as far as these are directly and unambiguously retrievable by a skilled person and to everything that as defined in the following set of claims

Claims

CLAIMS1 . Imaging system for imaging a specimen in an imaging space using an imaging signal with a frequency between 1 MHz and 500 MHz, the imaging system comprising:• a plurality of emitter devices provided distributed, preferably equally distributed, around the imaging space, wherein each emitter device comprises:- an emitter antenna which is configured for emitting an imaging signal, e.g. an electromagnetic imaging signal, to the specimen, wherein the emitter antenna has a send area that is electrically small compared to the imaging signal;; and- a current burst generator which is connected to the antenna for providing a current burst to the antenna for causing the emitter antenna to emit the imaging signal,• a plurality of receiver devices each comprising a receiver antenna, e.g. which has a receiver area that is electrically small compared to the imaging signal, for receiving a transmission signal from the specimen, wherein the transmission signal is caused by a transmission of an imaging signal through the imaging space;• a processor connected to each of the plurality of emitter devices for causing the current burst generators to provide the current burst causing the emitter antenna to emit the imaging signal and which processor is connected to each of the plurality of receiver devices so that the processor is configured to obtain, for each emitted imaging signal, a corresponding transmission signal representative of a transmission of the imaging signal through the imaging space and received by the receiver device, wherein each current burst generator comprises an electrical circuit operatively connected to the corresponding emitter antenna at an antenna connection location of the electrical circuit, wherein the electrical circuit comprises a MOSFET switch with an internal capacitance below 5 nF, a capacitor having a capacitance between 1 nF and 1 mF, and an inductor with an inductance between 50 nH and 1000 nH, wherein the antenna connection location is between the MOSFET switch and the inductor in the electrical circuit, and wherein the electrical circuit is connected to a power source for charging the capacitance, wherein the imaging system, e.g. the processor thereof, is configured to: consecutively cause each current burst generator to provide a current burst to the associated emitter antenna by: o charging the capacitor with the power source; o providing a switching signal between 0.1 MHz and 100 MHz to a gate of the MOSFET switch causing the MOSFET switch to switch from an open configuration to a closed configuration and back to the open configuration thereof generating the current burst with a burst peak above 50 V and a burst width below 1 ms and discharging the capacitor;consecutively emit, by the emitter antenna receiving the current burst, the imaging signal with a frequency between 1 MHz and 500 MHz, i.e. which emitting of the imaging signal is caused by the current burst; determine an image of the specimen in the imaging space based on a comparison of the received transmission signals to one or more calibration signals, e.g. obtained by performing a measurement of an imaging space without specimen therein.

2. Imaging system according to claim 1 , wherein each emitter device and an associated receiver device are embodied as an emitter-receiver device, e.g. wherein, each emitter-receiver device comprises a single antenna for emitting imaging signals and receiving transmission signals.

3. Imaging system according to one or more of the preceding claims, wherein each emitter antenna has a largest dimension of the effective send area smaller than 1 / 10th, preferably 1 / 50th, more preferably 1 / 100th, a wavelength of an emitted imaging signal.

4. Imaging system according to one or more of the preceding claims, wherein the effective send area of the antennas comprises conductive wires that are printed on a print surface.

5. Imaging system according to one or more of the preceding claims, wherein the antennas comprise an input wire which is at a first end thereof connected to the effective send area, e.g. and which is connected at another end thereof to the antenna connection location, and wherein the antennas comprise a termination wire which is at a first end thereof connected to the effective send area at a location opposite to the associated input wire.

6. Imaging system according to claim 5, wherein the input wire has a length of at least 50mm and the termination wire has a length between 5mm and 15mm.

7. Imaging system according to one or more of the preceding claims, wherein the emitter devices and receiver devices are provided moveably around the imaging space and wherein the imaging device is configured to move the emitter devices and / or the receiver devices between emitting and / or receiving signals.

8. Imaging system according to one or more of the preceding claims, wherein the imaging system comprises more than 10 emitter devices and more than 10 receiver devices.

9. Method for imaging a specimen wherein use is made of an imaging system according to one or more of the claims 1 - 8.

10. Method according to claim 9, wherein the method comprises: consecutively causing each current burst generator to provide a current burst to the associated emitter antenna by:o charging the capacitor with the power source; o providing a switching signal between 0.1 MHz and 100 MHz to a gate of the MOSFET switch causing the MOSFET switch to switch from an open configuration to a closed configuration and back to the open configuration thereof generating the current burst with a burst peak above 50 V and a burst width below 1 ms and discharging the capacitor; consecutively emitting, by the emitter antenna receiving the current burst, an imaging signal with a frequency between 1 MHz and 500 MHz, i.e. which emitting of the imaging signal is caused by the current burst; - determining an image of the specimen in the imaging space based on a comparison of the received transmission signals to one or more calibration signals, e.g. obtained by performing a measurement of an imaging space without specimen therein.

Images