CN117618797A

CN117618797A - Instant gamma imaging method, control device, electronic equipment and storage medium

Info

Publication number: CN117618797A
Application number: CN202311482084.2A
Authority: CN
Inventors: 汪金龙; 吴晓光; 郑云; 李聪博; 李天晓
Original assignee: China Institute of Atomic of Energy
Current assignee: China Institute of Atomic of Energy
Priority date: 2023-11-08
Filing date: 2023-11-08
Publication date: 2024-03-01

Abstract

The embodiment of the application discloses a prompt gamma imaging method, a control device, electronic equipment and a computer readable storage medium, and relates to the technical field of beam diagnosis and measurement. The method comprises the following steps: determining a detection field of view of the detector based on the size parameter of the grating hole; determining a target detection distance of the detector based on the detection field of view; adjusting the distance between the emission source and the grating hole to be larger than the target detection distance; and measuring the emission source by using the instantaneous gamma imaging device to obtain an instantaneous gamma image.

Description

Instant gamma imaging method, control device, electronic equipment and storage medium

Technical Field

The embodiment of the application relates to the technical field of beam diagnosis and measurement, in particular to a prompt gamma imaging method, a control device, electronic equipment and a computer readable storage medium.

Background

With the development of beam diagnosis and measurement technology, an instantaneous gamma image imaging technology appears, which is one of radiotherapy and is an internationally accepted radiotherapy tip imaging technology. Unlike conventional photon imaging techniques, transient gamma imaging can form energy bragg peaks that enable the positioning of particles within the body of a target object.

In the conventional technology, optimization of the instantaneous gamma image is realized by combining an optimized beam transmission system, an optimizing device and optimizing software. However, the accuracy of the resulting prompt gamma image is often not high due to the improper setting of the distance between the detector and the emission source.

Disclosure of Invention

In view of this, embodiments of the present application provide a prompt gamma imaging method, a control apparatus, an electronic device, and a computer-readable storage medium.

In order to achieve the above purpose, the technical solution of the embodiments of the present application is implemented as follows:

in a first aspect, an embodiment of the present application provides an instant gamma imaging method, for an instant gamma imaging device, where the gamma imaging device includes a detector including a plurality of grating holes arranged in rows and columns, the method including:

determining a detection field of view of the detector based on the size parameter of the grating hole;

determining a target detection distance of the detector based on the detection field of view;

adjusting the distance between the emission source and the grating hole to be larger than the target detection distance;

and measuring the emission source by using the instantaneous gamma imaging device to obtain an instantaneous gamma image.

In a second aspect, embodiments of the present application provide a prompt gamma imaging control device. The control device includes:

the first determining module is used for determining a detection view field of the detector based on the size parameters of the grating holes;

a second determining module, configured to determine a target detection distance of the detector based on the detection field of view;

the first adjusting module is used for adjusting the distance between the emission source and the grating hole to be larger than or equal to the target detection distance;

the first obtaining module is used for measuring the emission source by utilizing the instantaneous gamma imaging device to obtain an instantaneous gamma image.

In a third aspect, an embodiment of the present application provides an electronic device, including a memory and a processor, where the memory stores a computer program executable on the processor, and where the processor is capable of implementing steps in the method described above when the computer program is executed.

In a fourth aspect, embodiments of the present application provide a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, performs steps in the above-described method.

In the instant gamma imaging method provided by the embodiment of the application, firstly, the detection view field of a detector is determined based on the size parameter of the grating hole; and determining a target detection distance of the detector based on the detection field of view of the detector; on the basis, the distance between the emission source and the grating hole is adjusted to be larger than the target detection distance; and finally, measuring the emission source by utilizing the instantaneous gamma imaging device to obtain an instantaneous gamma pattern. By adjusting the distance between the emission source and the grating hole to be larger than the target detection distance, the independent detection view fields corresponding to the adjacent grating holes can be intersected, so that the probability of forming a full-energy peak by gamma rays passing through the grating holes can be improved, and the accuracy of the instant gamma image can be improved.

Drawings

Fig. 1 is a flowchart of an implementation of an instant gamma imaging method according to an embodiment of the present application;

FIG. 2 is a flowchart showing the implementation of step S11 in FIG. 1;

FIG. 3 is a schematic view of a basic detection field in an instant gamma imaging method according to an embodiment of the present application;

FIG. 4 is a schematic view of a detection field of a detector in an instant gamma imaging method according to an embodiment of the present disclosure;

FIG. 5 is a schematic view of a detection field of a detector in an instant gamma imaging method according to an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of a vertical arrangement of detectors in an embodiment of the present application;

FIG. 7 is a schematic diagram of the detectors arranged along the beam direction in an embodiment of the present application;

FIG. 8 is a flowchart showing the implementation of step S14 in FIG. 1;

FIG. 9 is a flowchart showing the implementation of step S142 in FIG. 8;

FIG. 10 is a flowchart showing the implementation of step S1422 in FIG. 9;

FIG. 11 is a schematic diagram of an instantaneous gamma energy spectrum before energy scaling in an embodiment of the present application;

FIG. 12 is a schematic diagram of an instantaneous gamma energy spectrum after energy scaling in an embodiment of the present application;

FIG. 13 shows the source after energy scaling in an embodiment of the present application ²³² Th and ²² an energy spectrum diagram of Na;

FIG. 14 is a schematic diagram of an instantaneous gamma energy window setup in an embodiment of the present application;

FIG. 15 is a schematic diagram of a gamma energy distribution radiation pattern in an embodiment of the present application;

FIG. 16 is a diagram illustrating a gamma energy distribution luminance graph according to an embodiment of the present application;

FIG. 17 is an exploded view of a detector in an embodiment of the present application;

FIG. 18 is an exploded schematic view of an instant gamma imaging device in an embodiment of the present application;

FIG. 19 is a schematic view of a structure of a probe according to an embodiment of the present application;

FIG. 20A is a schematic diagram of a detector in an instant gamma imaging device without dislocation arrangement in an embodiment of the present application;

FIG. 20B is a schematic diagram of a detector misalignment arrangement in a prompt gamma imaging device according to an embodiment of the present application;

FIG. 20C is a side view of a detector in an instant gamma imaging device in accordance with an embodiment of the present application;

FIG. 20D is a schematic view of a wedge plate in a prompt gamma imaging device according to an embodiment of the present application;

fig. 21 is a schematic diagram of an ADC board card function module in the embodiment of the application;

FIG. 22 is a schematic diagram of control logic of a probe according to an embodiment of the present application;

FIG. 23 is a schematic diagram of a composition structure of a prompt gamma imaging control device according to an embodiment of the present disclosure;

fig. 24 is a schematic diagram of a hardware entity of an electronic device in an embodiment of the present application.

Detailed Description

For the purposes, technical solutions and advantages of the embodiments of the present application to be more apparent, the specific technical solutions of the present application will be described in further detail below with reference to the accompanying drawings in the embodiments of the present application. The following examples are illustrative of the present application, but are not intended to limit the scope of the present application.

In the present embodiments, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the embodiments of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.

Furthermore, in the embodiments of the present application, the terms "upper," "lower," "left," and "right," etc., are defined with respect to the orientation in which the components in the drawings are schematically disposed, and it should be understood that these directional terms are relative terms, which are used for descriptive and clarity with respect to each other, and which may vary accordingly with respect to the orientation in which the components in the drawings are disposed.

In the embodiments of the present application, unless explicitly specified and limited otherwise, the term "connected" is to be construed broadly, and for example, "connected" may be fixedly connected, detachably connected, or integrally formed; can be directly connected or indirectly connected through an intermediate medium.

In the present embodiments, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

In the embodiments of the present application, words such as "exemplary" or "such as" are used to mean serving as examples, illustrations, or descriptions. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.

Flash gamma imaging is a method of monitoring proton radiation therapy in real time by detecting gamma rays emitted by the interaction of therapeutic radiation with the nucleus in the patient.

The principle of operation of prompt gamma imaging is to detect prompt gamma rays generated by the interaction of a proton beam with nuclei in a patient. The proton beam enters the body to generate nuclear reaction, the atomic nucleus enters a high-excitation state, and gamma rays are emitted when the atomic nucleus is instantaneously de-excited, and the instantaneously emitted gamma rays are instantaneously emitted gamma rays. The distribution of gamma rays is closely related to the position of the proton beam, and the range of the proton beam in the body can be verified by detecting the gamma rays.

For convenience of description, in the embodiments of the present application, a device that detects gamma rays and images is referred to as an instantaneous gamma imaging device. The instantaneous gamma imaging device comprises a detector and a processing module, wherein the detector is used for detecting gamma rays and converting the gamma rays into optical signals, and the processing module can convert the optical signals into electric signals for amplification and further process the electric signals to generate instantaneous gamma images.

In this application embodiment, the detector includes grating and scintillator, is provided with the grating hole on the grating, and after the gamma ray got into the scintillator through the grating hole, the scintillator absorbed gamma ray can give out light.

In the embodiment of the present application, the detector is formed by a plurality of grating holes arranged in rows and columns and corresponding scintillators. Illustratively, one scintillator is disposed at each end of each grating aperture.

On the basis, the embodiment of the application provides a prompt gamma imaging method.

It should be noted that, the prompt gamma imaging method provided in the embodiments of the present application may be executed by an electronic device, where the electronic device may be a notebook computer, a tablet computer, a desktop computer, a set-top box, a mobile device (for example, a mobile phone, a portable music player, a personal digital processing, a dedicated messaging device, a portable game device), or any other type of terminal, and may also be implemented as a server. The server may be an independent physical server, a server cluster or a distributed system formed by a plurality of physical servers, or a cloud server providing cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, content delivery networks (Content Delivery Network, CDN), basic cloud computing services such as big data and artificial intelligent platforms, and the like.

Referring to fig. 1, a flowchart of an implementation of a prompt gamma imaging method according to an embodiment of the present application is shown in fig. 1, where the method includes steps S11 to S14, where:

step S11, determining a detection view field of the detector based on the size parameters of the grating holes.

It will be appreciated that for a grating aperture, gamma rays may pass through the grating aperture to reach the scintillator, but not through other locations of the grating.

The size parameter of the grating hole refers to the geometric parameter information of the grating hole, and illustratively, in the embodiment of the present application, the cross section of the grating hole can be made into a square shape, for example, in some embodiments of the present application, the cross section size of the grating hole can be made into 5 mm×5 mm, and the length of the grating hole can be made into 80 mm. For this, the geometric parameter information of the grating holes refers to the length×width×height of the grating holes, i.e., 5×5×80 mm.

On this basis, the detection field of view of the detector can be represented by a partial area of the emission source, which is capable of emitting gamma rays to the scintillator via the grating aperture.

Corresponding to one grating aperture, it is considered that a partial region of the emission source facing each grating aperture, and other regions in the vicinity of the partial region, emit gamma rays that can reach the scintillator through the grating aperture. For convenience of description, the detection field of view corresponding to each grating aperture may be referred to as an independent detection field of view. And combining the independent detection fields corresponding to all the grating holes to obtain the detection field of the detector.

It will be appreciated that the detection field of view of the detector is determined based on the size parameters of the grating apertures. Illustratively, in the case of a larger cross-section of the grating aperture, the detection field of view of the detector is also larger; in the case of a smaller cross section of the grating aperture, the detection field of view of the detector is also smaller.

It will be appreciated that the use of the grating apertures corresponds to screening the gamma rays emitted by the source, thereby enabling some of the gamma rays emitted by the source to reach the scintillator. The partial gamma rays enable the scintillator to emit light signals.

Step S12, determining a target detection distance of the detector based on the detection field of view.

Here, the target detection distance of the detector may be determined based on the detection field of view of the detector on the basis of the parameter of the size of the grating hole.

It will be appreciated that the detection field of view of the detector is related to the distance between the source and the grating aperture, in addition to the parameters of the size of the grating aperture. Illustratively, in the case that the cross-sectional size of the grating hole is constant, in the case that the length of the grating hole is large, the detection field of view of the detector is small; in the case of a smaller length of the grating aperture, the detection field of view of the detector is larger.

It will be appreciated that by adjusting the distance between the emission source and the grating aperture, the individual detection fields of view of adjacent grating apertures can be separated, tangential or intersecting.

Here, the target detection distance is the distance between the emission source and the grating hole when the independent detection fields corresponding to adjacent grating holes are tangential.

And S13, adjusting the distance between the emission source and the grating hole to be larger than the target detection distance.

On the basis of determining the target detection distance of the detector in the previous step, the distance between the emission source and the grating hole can be adjusted so that the distance between the emission source and the grating hole is larger than the target detection distance.

Therefore, the independent detection view fields of the adjacent grating holes have the intersected parts, and the probability of forming a full-function peak by gamma rays passing through the grating holes can be improved.

And S14, measuring the emission source by using the instantaneous gamma imaging device to obtain an instantaneous gamma image.

On the basis, the instantaneous gamma imaging device is used for measuring the emission source, so that the instantaneous gamma graph corresponding to the emission source can be obtained.

In this way, in the prompt gamma imaging method provided in the embodiment of the present application, firstly, a detection field of view of a detector is determined based on a size parameter of a grating hole; and determining a target detection distance of the detector based on the detection field of view of the detector; on the basis, the distance between the emission source and the grating hole is adjusted to be larger than the target detection distance; and finally, measuring the emission source by utilizing the instantaneous gamma imaging device to obtain an instantaneous gamma pattern. By adjusting the distance between the emission source and the grating hole to be larger than the target detection distance, the independent detection view fields corresponding to the adjacent grating holes can be intersected, so that the probability of forming a full-energy peak by gamma rays passing through the grating holes can be improved, and the accuracy of the instant gamma image can be improved.

On this basis, the embodiment of the present application further provides a prompt gamma imaging method, referring to fig. 2, in which the above step S11 may be implemented through steps S111 to S113, where:

step S111, determining a basic detection field of view of the detector based on the size of the grating hole, wherein the basic detection field of view is used for representing the area of the emission source which can be measured by the detector along the axial direction of the grating hole.

For the emission source, it can be considered that each point on the emission source emits gamma rays toward all directions, and gamma rays moving along the axial direction of the grating hole among gamma rays emitted along a partial region of the emission source corresponding to the grating hole in the axial direction of the grating hole can reach the scintillator through the grating hole.

Here, the above-described area of the partial shape of the emission source corresponding to the grating hole in the axial direction of the grating hole may be referred to as a basic detection field of view.

By way of example, referring to fig. 3, it can be understood that, when the gamma photons emitted by the portion of the emission source located between S1 and S1' can move to the scintillator along the axial direction of the grating hole, taking the grating hole as a square as an example, the calculation formula of the basic detection field FOV1 is:

FOV1＝a ²

Wherein a is the side length of the grating hole.

Step S112, determining a marginal detection field of view of the detector based on the size of the grating hole, the marginal detection field of view being used to characterize an area of the basic detection field of view removed from an area of the emission source that the detector is able to measure along an edge of the grating hole.

It will be appreciated that, on the basis of the basic detection field of view described above, gamma rays emitted by the partial shape of the emission source located at the edge of the basic detection field of view can also reach the scintillator via the grating aperture.

Here, the marginal detection field of view may refer to an area of the emission source where gamma rays emitted in an area can reach the scintillator via the grating aperture after removing the fundamental detection field of view.

Referring to fig. 4, in some embodiments of the present application, an edge position of a scintillator at one end of a grating hole may be used as a reference, and a region of an emission source corresponding to a gamma ray capable of reaching the position may be used as a detection field of a detector, specifically, referring to fig. 4, a gamma ray emitted from a position of an emission source S2 moves to a position N2 along a straight line between a position S2 to a position N2 in the figure. Similarly, the gamma ray emitted from the S2 'position of the source moves to the N1 position along a straight line between the S2' position and the N1 position in the figure. For this, taking a grating hole as an example, the calculation formula of the marginal detection field of view FOVb is:

Then, the calculation formula of the detection field FOV2 of the detector is:

wherein a is the side length of the grating hole, d is the distance between the grating hole and the emission source, and H is the length of the grating hole.

It should be noted that, based on the foregoing description, it can be considered that each point on the emission source emits gamma rays toward all directions, and the probability that gamma rays emitted by the emission source located in the marginal detection field reach the scintillator is not the same. Here, the marginal detection field may be determined with a magnitude of probability that gamma rays emitted from an emission source located within the marginal detection field reach the scintillator, and a position where the probability that gamma rays emitted from the marginal detection field reach the scintillator is small may be discarded.

And step S113, adding the basic detection view field and the marginal detection view field to obtain the detection view field of the detector.

On this basis, the detection field of view of the detector can be obtained by adding the basic detection field of view and the marginal detection field of view.

In this way, in the prompt gamma imaging method provided by the embodiment of the application, the detection view field of the detector is obtained based on the basic detection view field and the marginal detection view field, so that the detection view field of the detector is more accurate, and the prompt gamma image obtained by using the prompt gamma imaging method provided by the embodiment of the application is more accurate.

On this basis, in some embodiments of the present application, the step S112 described above may be implemented by the following steps:

and taking the midpoint of the grating hole, which is far away from one end of the emission source, as a reference point, taking the edge of the reference point, which faces the grating hole and is close to one end of the emission source, as an auxiliary line, wherein the area of the area where the auxiliary line intersects with the emission source, excluding the area of the basic detection view field, is the marginal detection view field.

For example, referring to fig. 5, in some embodiments of the present application, a central position of a scintillator located in a grating hole may be taken as a reference, and a region of an emission source corresponding to a gamma ray capable of reaching the position may be taken as a detection field of view of a detector, and specifically, referring to fig. 5, a gamma ray emitted by a position of an emission source S3 moves along a straight line between a position S3 to a position N3 in the figure, and can reach the position N3. Similarly, the gamma ray emitted from the position of the emission source S3 'moves to the position N3 along a straight line between the position S3' and the position N3 in the figure, and for this purpose, taking the grating hole as a square as an example, the calculation formula of the marginal detection field of view FOVc is as follows:

then, the calculation formula of the detection field FOV3 of the detector is:

Therefore, the probability that the gamma rays in the marginal detection view field formed by the method form a full-energy peak is high, so that the accuracy of the instant gamma image in the embodiment of the application can be further improved.

For example, taking a 0.5 cm and h 80 mm as an example, a comparison of the detection fields of view at different distances for FOV1, FOV2 and FOV3 is shown in Table 1:

TABLE 1

Wherein d0 represents that the distance between the emission source and the grating hole is 0; d2 represents the distance between the emission source and the grating aperture is 0.75 cm; d3 represents that the distance between the emission source and the grating hole is 8 cm; d4 represents a distance between the source and the grating aperture of 15 cm.

In addition, in some embodiments of the present application, the step S12 described above may be implemented by the following steps:

and determining the target distance between the emission source and the grating holes when the detection view fields corresponding to adjacent grating holes in the grating holes arranged along the columns are tangential.

And taking the target distance as the target detection distance.

Here, among the grating holes arranged along the columns, the grating holes arranged along the columns can be considered as grating holes arranged in the horizontal direction.

On the basis, the detection view fields corresponding to the adjacent grating holes arranged along the columns can be separated, tangent and intersected by adjusting the distance between the emission source and the grating holes.

Here, the target distance between the emission source and the grating hole when the detection field of view of the detector corresponding to the adjacent grating hole among the grating holes arranged along the row is tangent is taken as the target detection distance.

In some embodiments of the present application, the detector may also be used as a subsequent composite prompt gamma image by calculating the lateral field angle of the detector. Referring to fig. 6, the calculation formula of the lateral field angle θ of the detector is:

wherein a is the side length of the grating hole, and H is the length of the grating hole.

And, the beam direction visible length of the detector can be determined based on the lateral field angle of the detector to be used as a subsequent synthesized prompt gamma image.

Referring to fig. 7, it can be understood that the detector units are arranged in parallel in the beam direction, and as the emission source is closer to the grating holes, the overlapping of detection fields corresponding to adjacent grating holes becomes smaller until no, and the independence of the detectors is better; when the target material is far away from the grating, the coincidence of detection fields corresponding to adjacent grating holes is larger, and the independence of the detectors is lower. The independence of the detector can be enhanced by increasing the grating length H. The visible length L of the beam direction of each detector is calculated by the radial scale information (a), the axial size information (H) and the object distance (d) of the grating, and the calculation formula is as follows:

It can be seen that decreasing either d or a, increasing H, increases the resolution in the beam direction. The detectors can be arranged in a staggered manner, which also corresponds to a reduction of a.

Thus, the above calculation can provide adjustability of the detector field of view for designing an array of a plurality of detectors to improve measurement accuracy.

In order to graphically illustrate the prompt gamma imaging method provided in embodiments of the present application, reference is made to fig. 17, which illustrates an example of a detector of the prompt gamma imaging device provided in some embodiments of the present application.

Specifically, referring to fig. 17, the detector 1 includes a grating 11, a scintillator 12, a silicon photomultiplier (Silicon photomultiplier, siPM) lineplate 13, an interposer 14, and an op-amp supply board 15. The grating hole 111 is provided in the grating.

Referring to fig. 18, in the embodiment of the present application, the prompt gamma imaging device includes a wedge plate 2 and a housing 3 in addition to the above-described detector 1, wherein a heat radiation window 31 is further provided on the housing 3.

On this basis, in some embodiments of the present application, the step S14 described above with reference to fig. 8 may be implemented by steps S141 to S142, where:

step S141, acquiring an instantaneous gamma energy spectrum of the emission source by using the detector.

Here, the scintillator may be used to detect gamma rays. Specifically, gamma rays strike a scintillator in a detector, the gamma rays lose and deposit energy in the scintillator, causing ionization excitation of atoms (or ions, molecules) in the scintillator, after which the excited particles are de-excited to emit scintillation photons having a wavelength close to that of visible light. When scintillation photons enter the SiPM, they interact with the silicon material in the photodiode. In a photodiode, photons are absorbed and excite some electrons, which will be accelerated and breakdown the PN junction, creating charge carriers. An amplifier in the photodiode amplifies these charge carriers and converts them into voltage pulses. The optical signal generated by the gamma rays acting on the scintillator is finally converted into an electrical signal. So that the analog signal obtained by signal conversion can be carried out through the circuit board of the detector.

And filtering the target photoelectric signal according to the signal conversion parameters to obtain a filtered photoelectric signal, wherein the filtered photoelectric signal can be a signal obtained by filtering the photoelectric signal.

Specifically, according to the photoelectric signal and the signal conversion parameter, selecting a target filter meeting the requirements from a plurality of filters, and inputting the photoelectric signal into the target filter for filtering to obtain a filtered photoelectric signal.

And then, the filtered photoelectric signals enter an operational amplifier power supply board through an adapter board to amplify the signals, so that analog signals are obtained. For example, ten signal output terminals and one power supply or communication port may be provided on the op amp power board.

Thus, the photoelectric signal is filtered and amplified to obtain the analog signal, so that the signal-to-noise ratio of the analog signal can be ensured to meet the requirement, and the accuracy of synthesizing the instantaneous gamma image is improved.

It will be appreciated that the output signal of the detector may also be compensated for depending on the different use circumstances of the detector. For example, the transmission line may be used directly to convert the photoelectric signal to an analog signal without compensating the parameters of the detector; under the condition that the parameters of the detector need to be compensated, the crystal parameters, gain information, reference voltage, siPM power supply temperature correction coefficients and the like of the detector can be adjusted, and then the photoelectric signals are converted into analog signals. Wherein the crystal parameters may be intrinsic parameters of individual scintillators of the scintillator array; the gain information may be a ratio between the photo signal and the analog model; the reference voltage can be the voltage value on the SiPM when the detector is placed in a temperature field (ice-water mixture) at 0 ℃ and the working current (100 mu A) is passed; the temperature compensation information may be a value of temperature compensation performed by the temperature compensation circuit on the sensitive element having a large temperature value drift.

Specifically, as shown in the following table, according to the crystal parameters of different scintillator arrays, it is necessary to determine different gain information or reference voltages, etc. to be configured, the integration time can be determined by observing waveforms, and all signals are positive signals. The voltage conversion circuit can convert the externally input 5V voltage into the bias voltage required by the SiPM and the positive and negative voltages required by the operational amplifier circuit respectively. The micro-program controller (Microprogrammed Control Unit, MCU) can generate temperature compensation information in real time by acquiring the temperature information of the scintillator to perform temperature compensation on the SiPM bias voltage, and can also control the digital potentiometer to adjust the gain of the front-end amplifier. Illustratively, referring to table 2, some compensation parameters are for different scintillators.

TABLE 2

Crystal body	Gain of	Voltage mV	Integration time ns	Signal polarity
					CsI	120	28.5	2000	+
LYSO	120	28.5	700	+
					BGO	115	28.5	150	+
LaBr3	127	26.8	400	+

Specifically, according to the signal conversion parameters, the functions of the SiPM line array plate, the adapter plate and the operational amplifier power supply plate in the detector are utilized to convert the photoelectric signals into analog signals to be output.

In this embodiment, by converting the target photoelectric signal into the target analog signal using the signal conversion parameter, the transient gamma image can be generated more accurately using the characteristics of the analog signal.

On the basis, the instantaneous gamma energy spectrum of the corresponding emission source can be obtained by carrying out subsequent processing on the analog signal.

In this embodiment, by determining the gain information, the reference voltage, and the temperature compensation information by using the crystal parameters of the scintillator and the target photoelectric signal, appropriate signal conversion parameters can be set in combination with different crystals and circuit characteristics of the circuit board, so that the target analog signal is prevented from being distorted after the target photoelectric signal is converted into the target analog signal.

Step S142, obtaining an instantaneous gamma image based on the instantaneous gamma energy spectrum.

It should be noted that, in the embodiment of the present application, the Analog-to-DigitalConverter, ADC (Analog-to-DigitalConverter, ADC) board card may be used to digitize the instantaneous gamma spectrum. For example, in the embodiment of the application, 4 32-channel ADC boards may be used to digitally process the signal of the instantaneous gamma energy spectrum to obtain the instantaneous gamma pattern. Specifically, the input interface of the ADC board card is LEMO, so that the design requirement of the detector can be met. Each ADC board card comprises 8 4-channel ADC3424 chips, the sampling rate is 125M, the resolution is 12 bits, the input range is-1V to 1V, and the input range can be expanded to-2V to 2V after the gain is matched through a front-end amplifying circuit. Each ADC board card is also provided with 1 Kintex-7xc7k325t FPGA chip for processing digital signals output by the ADC and controlling the HDMI high-speed data transmission interface and the data transmission protocol of the gigabit network port chip configured on the ADC board card, an independent working mode can be realized through communication between the gigabit network port and a computer host, synchronous data acquisition of multiple boards can be realized through transmitting data to an upper data summarizing card through the HDMI interface, and a functional module schematic diagram of the ADC board card is shown in FIG. 21.

On the basis, the instantaneous gamma image can be obtained through the instantaneous gamma energy spectrum.

On this basis, in some embodiments of the present application, referring to fig. 9, the above-mentioned step S142 may be implemented by steps S1421 to S1423, wherein:

step S1421, performing energy scale processing on the instantaneous gamma energy spectrum based on an energy scale formula to obtain an aligned energy spectrum.

The energy scale formula may be a mathematical expression for correlating the amplitude of the signal measured by the detector with the corresponding gamma ray energy. It will be appreciated that the energy scale formula may be derived from calibration of the emission source.

The alignment of the energy spectra may be, among other things, the adjustment of the energy spectra (energy profiles) of different measurement or data sources to a common standard for comparison, analysis or merging of these energy spectra. The purpose of the alignment of the spectra is to ensure that the energy axes of the spectra are consistent for efficient data processing and interpretation.

Specifically, the amplitude of a signal of an instantaneous gamma energy spectrum of an instantaneous gamma image is substituted into an energy scale formula, each channel address and each energy peak are fitted by a quadratic function by utilizing the energy scale formula, and when unknown energy is detected, the energy can be read out through the channel address, namely the energy scale. Exemplary, as shown in fig. 11, is a schematic of the energy spectrum prior to the energy scaling process. After the energy scaling process, all signals are given energy values, so that an aligned energy spectrum can be obtained. The alignment spectrum is a histogram, the horizontal axis represents the energy of the gamma ray, the vertical axis represents the signal count in the corresponding energy range, and as shown in fig. 12, the alignment spectrum is a schematic diagram of the energy spectrum after the energy scale process is performed, so that the energy distribution situation of the gamma ray can be shown. As shown in FIG. 13, the radioactive source is shown after calibration ²³² Th and ²² as can be seen from the spectrum diagram of Na, three low energy peaks 583kev,911kev and 1460kev are selected for LaBr3, and three high energy peaks 911kev,1460kev and 2614kev are selected for BGO.

Step S1422, counting each channel in the alignment spectrum to obtain the gamma energy distribution brightness map.

The gamma energy distribution luminance map may be a luminance map of a distribution of the emission source at different energies.

Specifically, in the step, energy window selection may be performed in the aligned energy spectrum, where the selected energy window includes at least one statistical channel, and each statistical channel has a corresponding channel address. The counts in each statistical channel are statistically processed, which typically includes calculating the total number or count rate of gamma ray counts in each statistical channel. These counts can be used to represent gamma ray brightness for each energy range. Wherein the statistical model must fulfil the following functions: related device parameters may be configured including SiPM reference voltage, gain information, integration time, threshold, signal polarity, energy window range, etc.; acquiring waveform and energy spectrum data of all detectors; the energy spectrum and waveform data can be displayed in real time, and the X and Y axes can be displayed in logarithmic form; the energy spectrum can be graduated; the energy window can be clamped, any energy range can be realized, an interface can be displayed independently, and data can be stored; integrating the amount of the energy obtained by the card, and storing an integration result according to a channel; a brightness display window of energy integration count; the system is provided with an offline analysis module, the energy window and subsequent operation can be also blocked, and data in a specified time period can be intercepted for analysis in an offline mode.

Finally, a gamma energy distribution luminance map can be obtained.

Step S143, obtaining the prompt gamma image based on the gamma energy distribution brightness map.

Here, on the basis of the obtained gamma energy distribution luminance map, an instantaneous gamma image can be obtained.

On this basis, in some embodiments of the present application, referring to fig. 10, the above-mentioned step S1422 may be implemented by steps S14221 to S14224, wherein:

step S14221, determining an instantaneous gamma energy window corresponding to the instantaneous gamma image based on the aligned energy spectrum.

Wherein the prompt gamma energy window may be used to select a particular energy range to capture a range of a particular type of radioactive signal.

In particular, one or more energy ranges of interest are selected in the aligned energy spectrum, where these energy ranges generally correspond to the particular gamma ray energy spectrum characteristics of the study. A threshold or energy threshold is further determined for defining upper and lower limits of the prompt gamma energy window, the threshold being either a count value for a particular energy spectrum channel or a value related to signal-to-noise ratio. Finally, the selected energy range is combined with a threshold to determine an instantaneous gamma energy window. Typically, the instantaneous gamma energy window consists of a lower energy limit and an upper energy limit, defining the gamma ray energy range of interest. As shown in FIG. 14, the instantaneous gamma energy window of interest can be selected from the aligned spectra, and the groups can be arbitrarily set and expressed in different colors.

Step S14222, determining a statistical channel corresponding to the transient gamma image based on the transient gamma energy window.

Wherein the statistical channel may be a discrete region or channel for dividing the gamma ray spectral data into different energy ranges. Each statistical channel represents a particular energy range and is used to record the count or count rate of gamma rays within that range. The purpose of the statistical channel is to discretize the gamma ray spectrum for analysis, visualization, and data extraction.

Specifically, the entire energy window range is divided into a plurality of statistical channels based on the image data after the selected prompt gamma energy window. The statistical channel divides the whole energy range into a plurality of discrete sub-ranges so as to analyze gamma rays in different energy intervals. These sub-ranges may be of equal width or non-uniformly divided according to study requirements. For each statistical channel, a count or count rate of gamma rays is recorded, representing the number of gamma ray events detected within the energy range. These counts can be used to study the energy spectrum distribution of gamma rays.

Step S14223, counting the radiant energy based on the counting channel, to obtain the gamma energy distribution radiation pattern.

Here, the gamma energy distribution radiation pattern may be a radiation pattern showing the distribution of a radiation source or a gamma source emitted by a particle in a nuclear reaction of a substance.

Specifically, the gamma ray count data in each statistical channel is integrated into one data set, and a histogram is generated according to the channel number arrangement using the integrated data, and a gamma energy distribution radiation pattern is created, as shown in fig. 15. This is typically a two-dimensional image, where the horizontal axis represents the energy range of gamma rays and the vertical axis represents the gamma ray count or count rate within the corresponding energy range. The gamma energy profile may be presented by data visualization tools or software. By selecting different chart types, such as histograms, line graphs or heat maps, the energy distribution is better visualized.

Step S14224, obtaining the gamma energy distribution brightness map based on the gamma energy distribution radiation map.

Here, the data in the gamma energy distribution radiation pattern may be normalized to ensure that the brightness value of the image has a proper range when visualized, which may be accomplished by dividing the data by a maximum count value or count rate, scaling the data range to between 0 and 1. Using the normalized data, a gamma energy distribution luminance map is created as shown in fig. 16. Wherein creating a gamma energy distribution luminance map may be accomplished using image processing tools or software, the luminance values of the images will correspond to the intensity or count rate of gamma rays within the corresponding energy range.

In this embodiment, by using the correspondence between each channel address and energy in the prompt gamma image, a gamma energy distribution radiation pattern is generated, and further converted into a gamma energy distribution brightness pattern according to the gamma energy distribution radiation pattern, the accuracy of the gamma energy distribution brightness pattern can be ensured based on the relationship between the distribution condition of the gamma source or the particle emitted by the nuclear reaction of the substance and the channel.

By counting the instant gamma images according to each channel, a gamma energy distribution brightness map is obtained, and the distribution condition of the radioactive source under different energies can be obviously seen under the condition of ensuring high contrast.

On the basis, the embodiment of the application also provides a prompt gamma imaging device. Referring to fig. 17 to 20, the instant gamma imaging device includes three detectors 1 arranged in a layered manner. A wedge plate 2 is arranged between the adjacent detectors 1, one side of the wedge plate 2 facing the grating is thinner, and one side of the wedge plate 2 away from the grating is thicker. In some embodiments of the present application, the angle of the wedge plate may be set to 4 degrees.

On this basis, referring to fig. 17, in some embodiments of the present application, each detector includes an arrayed grating, a scintillator array, an SiPM line shelf, an interposer, and an op-amp power panel.

The grating holes are arranged in the grating. The material of the grating is tantalum or other heavy element metal, so that gamma rays passing through the grating holes can reach the scintillator, and other gamma rays are blocked in the grating shell and cannot enter the scintillator.

In the embodiment of the present application, the type of the scintillator is not limited, and lanthanum bromide (LaBr 3) or Bismuth Germanate (BGO) or the like may be selected to provide the scintillator, for example. Wherein, the encapsulation of the scintillator can be decided according to the comprehensive consideration of the process details. The crystal is different from one crystal to another, the use environment is different from one crystal to another, and the packaging reflection material is different from one crystal to another. Illustratively, polytetrafluoroethylene film, titanium dioxide, lanthanum bromide, or the like may be selected to encapsulate the crystal.

In one embodiment, the scintillator size may be set to be different, such as LaBr3 may be set to 5×5×50 millimeters, 3×3×50 millimeters, or 5×5×50 millimeters. In addition, the scintillator may be provided in a small-crystal honeycomb structure, which can enhance the position resolution.

The reflection layer may be coated on the outer layer of LaBr3 crystal, and the material of the reflection layer may be teflon. There is no reflective layer on top of the LaBr3 crystal, which allows visible photons to enter the SiPM. Further, the thickness of the reflective layer may be set to 0.25 mm. On the basis of this, outside the reflective layer is an aluminum housing, which can be set to a thickness of 1 mm. It should be noted that, the top of the reflecting layer has no aluminum shell, but a window made of glass, and the thickness can be set to 2 mm to ensure light transmission efficiency.

Using radioactive sources ²² The energy resolution of LaBr3 at 511KeV was much higher than that of other crystals, BGO had a distinct peak shape at 1274KeV, and the detection efficiency was higher for 5×5×50 mm than for 3×3×50 mm for other crystals, as shown in table 3 below, for different scintillators under comparable conditions. Thus, in some embodiments of the present application, the scintillator is set to be both LaBr3 and BGO crystals. The specification is 5×5×50 mm. The pixel size is designed to be 1 square centimeter considering the crystal package size.

TABLE 3 Table 3

Gauss fitting	CsI	LYSO	BGO	LaBr3
					Pole value	511.8115	510.8476	510.7318	511.2268
Half width of height	116.1711	185.7438	182.0949	58.76364
					Peak value	162.7914	747.6702	800.8151	291.1153
Peak area	20130.83	147828	155225.2	18209.83
					Resolution ratio	22.70％	36.36％	35.65％	11.49％

The wedge material may be provided as a high atomic number metal, such as tantalum, and the angle of the wedge may be set to 4 degrees or other angles. In addition, the angle of the wedge block can be set to be adjustable so as to adapt to different isocenter distances. Wherein, any wedge block is positioned between two adjacent detectors; the difference between the number of detectors and the number of wedges is 1. In one embodiment, the detectors are arranged in a staggered manner, as shown in fig. 20A, the instantaneous gamma detector is made of LaBr3 material, and the instantaneous gamma detector is made of BGO material in sequence from top to bottom. Each detector has 10 pixels with a pitch of 1 cm. The off-white portion is the grating mask. The grating holes are square holes with the size of 0.5 multiplied by 0.5 cm. The grating shielding functions to filter the photons so that only gamma rays parallel to the grating apertures enter the scintillator. This feature ensures that the detector can detect the bragg peak position and thus measure the proton range. However, the interval between pixels in the prompt gamma detection module is 1 cm, so that the prompt gamma detection module may be arranged in a staggered manner to achieve high-precision measurement, as shown in fig. 20B. The offset arrangement of the two detectors can improve the precision to 0.5 cm, the offset arrangement of the three detectors can improve the precision to 0.33 cm, and the offset arrangement of the ten detectors can improve the precision to 0.1 cm. The premise of this misalignment measurement method is that all detectors should see the beam center plane at the same time. Thus, a wedge is used to form the angle between the two detectors, as shown in fig. 20C and 20D. In one exemplary embodiment, the wedge ramp angle is the same as the angle value of the detector included angle.

In the embodiment, the wedge-shaped blocks are added into two adjacent detectors, so that a detector included angle exists between the two adjacent detectors, and the detector included angle can be adjusted; and the different detectors are arranged in a staggered way, so that each different detector can correspond to the same central position, and the measurement accuracy is improved.

In addition, the instant gamma imaging device provided in the embodiment of the present application further includes a first light shield 6, a second light shield 7, a third light shield 8, and a connecting piece 9. The first light shield wraps the joint of the grating and the crystal array, and the first light shield and the grating are fixed through the connecting piece; the second light shield wraps the crystal array, and in the moving direction of the target gamma rays, the first light shield is rigidly connected with the second light shield; the third light shield wraps the junction of the crystal array and the circuit board, and in the moving direction of the target gamma rays, the second light shield is rigidly connected with the third light shield.

The first light shield, the second light shield and the third light shield are all made of black polymers, the first light shield is meshed with the second light shield, the third light shield is meshed with the second light shield, meanwhile, the SiPM line strake is wrapped by the third light shield, the whole light path is sealed, and natural clutter is prevented from entering the crystal.

The connecting piece is made of aluminum, and the grating and the second light shield are connected through threads, so that the external threaded holes of the connecting piece and the screws play a role in adjusting the longitudinal position.

In one embodiment, the grating length is 80 mm, the grating through hole is 5×5 mm, just the cross-sectional size of the crystal; the maximum energy of the protons is 230MeV, and the range in water is about 33 cm; a proton range of 100MeV of about 7.7 cm; a longitudinal depth of about 10 cm is measured; each pixel is 1 cm in size, 10 pixels are required for each detector. The assembled probe is shown in fig. 19.

Referring to fig. 22, a logic diagram of the circuit operation of the detector is shown.

On this basis, the embodiment of the present application further provides an instant gamma imaging control device, fig. 23 is a schematic structural diagram of the instant gamma imaging control device provided in the embodiment of the present application, as shown in fig. 23, the control device 2300 includes a first determining module 2301, a second determining module 2302, a first adjusting module 2303, and a first obtaining module 2304, where:

the first determining module 2301 is configured to determine a detection field of view of the detector based on a size parameter of the grating aperture.

The second determining module 2302 is configured to determine a target detection distance of the detector based on the detection field of view.

The first adjustment module 2303 is configured to adjust a distance between the emission source and the grating aperture to be greater than or equal to the target detection distance.

The first obtaining module 2304 is configured to measure the emission source with the prompt gamma imaging device to obtain a prompt gamma image.

It should be noted that, in the embodiment of the present application, if the foregoing prompt gamma imaging method is implemented in the form of a software functional module, and sold or used as a separate product, the prompt gamma imaging method may also be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the embodiments of the present application may be essentially or partially contributing to the related art, and the computer software product may be stored in a storage medium, and include several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read Only Memory (ROM), a magnetic disk, an optical disk, or other various media capable of storing program codes. Thus, embodiments of the present application are not limited to any specific combination of hardware and software.

Correspondingly, the embodiment of the application provides electronic equipment, which comprises a memory and a processor. The memory is used for storing a computer program which can be run on the processor. The processor is adapted to implement the steps in the method provided in the above embodiments when executing the computer program.

Accordingly, embodiments of the present application provide a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the methods provided in the above embodiments.

It should be noted that, fig. 24 is a schematic diagram of a hardware entity of an electronic device in an embodiment of the present application, as shown in fig. 24, the hardware entity of the electronic device 2400 includes: processor 2401, communication interface 2402, and memory 2403, wherein:

processor 2401 generally controls the overall operation of electronic device 2400.

The communication interface 2402 may enable the electronic device to communicate with other terminals or servers over a network.

The memory 2403 is configured to store instructions and applications executable by the processor 2401, and may also cache data (e.g., image data, audio data, voice communication data, and video communication data) to be processed or processed by each module in the processor 2401 and the electronic device 2400, which may be implemented by a FLASH memory (FLASH) or a random access memory (Random Access Memory, RAM). Data transfer may occur between processor 2401, communication interface 2402 and memory 2403 via bus 2404.

It should be noted here that: the description of the storage medium and apparatus embodiments above is similar to that of the method embodiments described above, with similar benefits as the method embodiments. For technical details not disclosed in the embodiments of the storage medium and the apparatus of the present application, please refer to the description of the method embodiments of the present application for understanding.

It should be appreciated that reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. It should be understood that, in various embodiments of the present application, the sequence numbers of the foregoing processes do not mean the order of execution, and the order of execution of the processes should be determined by the functions and internal logic thereof, and should not constitute any limitation on the implementation process of the embodiments of the present application. The foregoing embodiment numbers of the present application are merely for describing, and do not represent advantages or disadvantages of the embodiments.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other ways. The above described device embodiments are only illustrative, e.g. the division of the units is only one logical function division, and there may be other divisions in practice, such as: multiple units or components may be combined or may be integrated into another system, or some features may be omitted, or not performed. In addition, the various components shown or discussed may be coupled or directly coupled or communicatively coupled to each other via some interface, whether indirectly coupled or communicatively coupled to devices or units, whether electrically, mechanically, or otherwise.

The units described above as separate components may or may not be physically separate, and components shown as units may or may not be physical units; can be located in one place or distributed to a plurality of network units; some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment. In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may be separately used as one unit, or two or more units may be integrated in one unit; the integrated units may be implemented in hardware or in hardware plus software functional units.

Those of ordinary skill in the art will appreciate that: all or part of the steps for implementing the above method embodiments may be implemented by hardware related to program instructions, and the foregoing program may be stored in a computer readable storage medium, where the program, when executed, performs steps including the above method embodiments; and the aforementioned storage medium includes: a mobile storage device, a Read Only Memory (ROM), a magnetic disk or an optical disk, or the like, which can store program codes.

Alternatively, the integrated units described above may be stored in a computer readable storage medium if implemented in the form of software functional modules and sold or used as a stand-alone product. Based on such understanding, the technical solutions of the embodiments of the present application may be essentially or partially contributing to the related art, and the computer software product may be stored in a storage medium, and include several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a removable storage device, a ROM, a magnetic disk, or an optical disk.

The foregoing is merely an embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes and substitutions are intended to be covered in the protection scope of the present application.

Claims

1. A prompt gamma imaging method for a prompt gamma imaging device, the gamma imaging device comprising a detector including a plurality of grating apertures arranged in rows and columns, the method comprising:

2. The method of claim 1, wherein the determining a detection field of view of the detector based on the grating aperture size parameter comprises:

determining a basic detection field of view of the detector based on the size of the grating aperture, the basic detection field of view being used to characterize an area of the emission source that the detector is able to measure along an axial direction of the grating aperture;

determining a marginal detection field of view of the detector based on the size of the grating aperture, the marginal detection field of view being used to characterize an area of the emission source along an edge of the grating aperture that the detector is capable of measuring, excluding an area of the basic detection field of view;

and adding the basic detection view field and the marginal detection view field to obtain the detection view field of the detector.

3. The method of claim 2, wherein the determining a marginal detection field of view of the detector based on the grating aperture size comprises:

4. The method of claim 2, wherein the determining the target detection distance of the detector based on the detection field of view comprises:

determining a target distance between the emission source and the grating holes when the detection view fields corresponding to adjacent grating holes in the grating holes arranged along the columns are tangential;

and taking the target distance as the target detection distance.

5. The method of claim 1, wherein measuring the emission source with the prompt gamma imaging device to obtain a prompt gamma image comprises:

utilizing the detector to acquire an instantaneous gamma energy spectrum of the emission source;

and obtaining the instantaneous gamma image based on the instantaneous gamma energy spectrum.

6. The method of claim 5, wherein the deriving the prompt gamma image based on the prompt gamma energy spectrum comprises:

Performing energy scale processing on the instantaneous gamma energy spectrum based on an energy scale formula to obtain an aligned energy spectrum;

counting all channels in the alignment energy spectrum to obtain a gamma energy distribution brightness map;

and obtaining the instant gamma image based on the gamma energy distribution brightness map.

7. The method of claim 6, wherein the counting each channel in the aligned spectrum to obtain a gamma energy distribution luminance map comprises:

determining an instantaneous gamma energy window corresponding to the instantaneous gamma image based on the alignment energy spectrum;

based on the instantaneous gamma energy window, determining a statistical channel corresponding to the instantaneous gamma image;

counting radiation energy based on the counting channel to obtain the gamma energy distribution radiation diagram;

and obtaining the gamma energy distribution brightness map based on the gamma energy distribution radiation map.

8. An instantaneous gamma imaging control device, comprising:

9. An electronic device comprising a memory and a processor, the memory storing a computer program executable on the processor, the processor being capable of implementing the steps of the method of any one of claims 1 to 7 when the computer program is executed.

10. A computer-readable storage medium, characterized in that a computer program is stored thereon, which, when being executed by a processor, realizes the steps in the method of any of claims 1 to 7.