WO2024031595A1

WO2024031595A1 - Radiation detecting systems with measurement results adjusted according to radiation source intensities

Info

Publication number: WO2024031595A1
Application number: PCT/CN2022/111958
Authority: WO
Inventors: Peiyan CAO; Yurun LIU
Original assignee: Shenzhen Xpectvision Technology Co., Ltd.
Priority date: 2022-08-12
Filing date: 2022-08-12
Publication date: 2024-02-15
Also published as: TW202407386A

Abstract

A system (500) including a radiation source (520) configured to send an excitation radiation beam (525e) from the radiation source (520) toward an object (540) thereby causing emission of XRF radiation (545) from the object (540), and configured to send a control radiation beam (525c) from the radiation source (520). The system (500) is configured to determine an apparent intensity of the XRF radiation (545), to determine a control intensity of the control radiation beam (525c), and to determine a normalized intensity of the XRF radiation based on the apparent intensity of the XRF radiation (545) and the control intensity of the control radiation beam (525c).

Description

RADIATION DETECTING SYSTEMS WITH MEASUREMENT RESULTS ADJUSTED ACCORDING TO RADIATION SOURCE INTENSITIES

Background

A radiation detector is a device that measures a property of a radiation. Examples of the property may include a spatial distribution of the intensity, phase, and polarization of the radiation. The radiation measured by the radiation detector may be a radiation that has transmitted through an object. Alternatively, the radiation measured by the radiation detector may be characteristic X-rays emitted by an element in the object via X-ray fluorescence (XRF) . XRF is the emission of characteristic X-rays from the element that has been excited by, for example, exposure to high-energy X-rays or gamma rays. The radiation measured by the radiation detector may be electromagnetic radiation such as infrared light, visible light, ultraviolet light, X-ray, or γ-ray. The radiation may be of other types such as α-rays and β-rays. An imaging system may include one or more image sensors each of which may have one or more radiation detectors.

Summary

Disclosed herein is a system comprising a radiation source configured to send an excitation radiation beam from the radiation source toward an object thereby causing emission of XRF (X-ray fluorescent) radiation from the object, and configured to send a control radiation beam from the radiation source. The system is configured to determine an apparent intensity of the XRF radiation, to determine a control intensity of the control radiation beam, and to determine a normalized intensity of the XRF radiation based on the apparent intensity of the XRF radiation and the control intensity of the control radiation beam.

In an aspect, an intensity of the excitation radiation beam is related to an intensity of the control radiation beam.

In an aspect, an intensity of the excitation radiation beam is equal to an intensity of the control radiation beam.

In an aspect, the apparent intensity of the XRF radiation and the control intensity of the control radiation beam are determined for a first time point and a second time point respectively, and the first time point is temporally related to the second time point.

In an aspect, the first time point and the second time point are the same.

In an aspect, the system further comprises a main radiation detector configured to measure the apparent intensity of the XRF radiation.

In an aspect, the main radiation detector does not receive any radiation particle from the radiation source.

In an aspect, the system further comprises a blocking device configured to prevent all radiation particles from the radiation source and aimed at the main radiation detector from reaching the main radiation detector.

In an aspect, the system further comprises a monitoring radiation detector configured to measure the control intensity of the control radiation beam.

In an aspect, no radiation particle from the radiation source and aimed at the object hits the monitoring radiation detector.

In an aspect, the monitoring radiation detector is stationary with respect to the radiation source.

In an aspect, the system further comprises an attenuation device configured to attenuate the control radiation beam by an attenuation ratio resulting in an attenuated control radiation beam; a monitoring radiation detector configured to measure an intensity of the attenuated control radiation beam; and a controller configured to calculate the control intensity of the control radiation beam based on (A) the intensity of the attenuated control radiation beam and (B) the attenuation ratio.

In an aspect, the normalized intensity of the XRF radiation divided by the apparent intensity of the XRF radiation equals a pre-determined base intensity of the control radiation beam divided by the control intensity of the control radiation beam.

In an aspect, the excitation radiation beam comprises X-rays, and the control radiation beam comprises X-rays.

Disclosed herein is a method, comprising: sending an excitation radiation beam from a radiation source toward an object thereby causing emission of XRF (X-ray fluorescent) radiation from the object; sending a control radiation beam from the radiation source; determining an apparent intensity of the XRF radiation; determining a control intensity of the control radiation beam; and determining a normalized intensity of the XRF radiation based on (a) the apparent intensity of the XRF radiation and (b) the control intensity of the control radiation beam.

In an aspect, the first time point and the second time point are the same.

In an aspect, said determining the apparent intensity of the XRF radiation comprises measuring the apparent intensity with a main radiation detector.

In an aspect, all radiation particles from the radiation source and aimed at the main radiation detector are prevented from reaching the main radiation detector.

In an aspect, said determining the control intensity of the control radiation beam comprises measuring the control intensity with a monitoring radiation detector.

In an aspect, said determining the control intensity of the control radiation beam comprises: attenuating the control radiation beam by an attenuation ratio resulting in an attenuated control radiation beam; measuring an intensity of the attenuated control radiation beam with a monitoring radiation detector; and calculating the control intensity of the control radiation beam based on (A) the intensity of the attenuated control radiation beam and (B) the attenuation ratio.

Brief Description of Figures

Fig. 1 schematically shows a radiation detector, according to an embodiment.

Fig. 2 schematically shows a simplified cross-sectional view of the radiation detector, according to an embodiment.

Fig. 3 schematically shows a detailed cross-sectional view of the radiation detector, according to an embodiment.

Fig. 4 schematically shows a detailed cross-sectional view of the radiation detector, according to an alternative embodiment.

Fig. 5 schematically shows a radiation detecting system, according to an embodiment.

Fig. 6 shows a flowchart generalizing the operation of the radiation detecting system, according to an embodiment.

Fig. 7 schematically shows the radiation detecting system, according to an alternative embodiment.

Detailed Description

RADIATION DETECTOR

Fig. 1 schematically shows a radiation detector 100, as an example. The radiation detector 100 may include an array of pixels 150 (also referred to as sensing elements 150) . The array may be a rectangular array (as shown in Fig. 1) , a honeycomb array, a hexagonal array, or any other suitable array. The array of pixels 150 in the example of Fig. 1 has 4 rows and 7 columns; however, in general, the array of pixels 150 may have any number of rows and any number of columns.

Each pixel 150 may be configured to detect radiation from a radiation source (not shown) incident thereon and may be configured to measure a characteristic (e.g., the energy of the particles, the wavelength, and the frequency) of the radiation. The radiation may include radiation particles such as photons (X-rays, gamma rays, etc. ) and subatomic particles (alpha particles, beta particles, etc. ) Each pixel 150 may be configured to count numbers of particles of radiation incident thereon whose energy falls in a plurality of bins of energy, within a period of time. All the pixels 150 may be configured to count the numbers of particles of radiation incident thereon within a plurality of bins of energy within the same period of time. When the incident particles of radiation have similar energy, the pixels 150 may be simply configured to count numbers of particles of radiation incident thereon within a period of time, without measuring the energy of the individual particles of radiation.

Each pixel 150 may have its own analog-to-digital converter (ADC) configured to digitize an analog signal representing the energy of an incident particle of radiation into a digital signal, or to digitize an analog signal representing the total energy of a plurality of incident particles of radiation into a digital signal. The pixels 150 may be configured to operate in parallel. For example, when one pixel 150 measures an incident particle of radiation, another pixel 150 may be waiting for a particle of radiation to arrive. The pixels 150 may not have to be individually addressable.

The radiation detector 100 described here may have applications such as in an X-ray telescope, X-ray mammography, industrial X-ray defect detection, X-ray microscopy or microradiography, X-ray casting inspection, X-ray non-destructive testing, X-ray weld inspection, X-ray digital subtraction angiography, etc. It may be suitable to use this radiation detector 100 in place of a photographic plate, a photographic film, a PSP plate, an X-ray image intensifier, a scintillator, or another semiconductor X-ray detector.

Fig. 2 schematically shows a simplified cross-sectional view of the radiation detector 100 of Fig. 1 along a line 2-2, according to an embodiment. Specifically, the radiation detector 100 may include a radiation absorption layer 110 and an electronics layer 120 (which may include one or more ASICs or application-specific integrated circuits) for processing and analyzing electrical signals which incident radiation generates in the radiation absorption layer 110. The radiation detector 100 may or may not include a scintillator (not shown) . The radiation absorption layer 110 may include a semiconductor material such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof. The semiconductor material may have a high mass attenuation coefficient for the radiation of interest.

Fig. 3 schematically shows a detailed cross-sectional view of the radiation detector 100 of Fig. 1 along the line 2-2, as an example. Specifically, the radiation absorption layer 110 may include one or more diodes (e.g., p-i-n or p-n) formed by a first doped region 111, one or more discrete regions 114 of a second doped region 113. The second doped region 113 may be separated from the first doped region 111 by an optional intrinsic region 112. The discrete regions 114 may be separated from one another by the first doped region 111 or the intrinsic region 112. The first doped region 111 and the second doped region 113 may have opposite types of doping (e.g., region 111 is p-type and region 113 is n-type, or region 111 is n-type and region 113 is p-type) . In the example of Fig. 3, each of the discrete regions 114 of the second doped region 113 forms a diode with the first doped region 111 and the optional intrinsic region 112. Namely, in the example in Fig. 3, the radiation absorption layer 110 has a plurality of diodes (more specifically, 7 diodes corresponding to 7 pixels 150 of one row in the array of Fig. 1, of which only 2 pixels 150 are labeled in Fig. 3 for simplicity) . The plurality of diodes may have an electrical contact 119A as a shared (common) electrode. The first doped region 111 may also have discrete portions.

The electronics layer 120 may include an electronic system 121 suitable for processing or interpreting signals generated by the radiation incident on the radiation absorption layer 110. The electronic system 121 may include an analog circuitry such as a filter network, amplifiers, integrators, and comparators, or a digital circuitry such as a microprocessor, and memory. The electronic system 121 may include one or more ADCs (analog to digital converters) . The electronic system 121 may include components shared by the pixels 150 or components dedicated to a single pixel 150. For example, the electronic system 121 may include an amplifier dedicated to each pixel 150 and a microprocessor shared among all the pixels 150. The electronic system 121 may be electrically connected to the pixels 150 by vias 131. Space among the vias may be filled with a filler material 130, which may increase the mechanical stability of the connection of the electronics layer 120 to the radiation absorption layer 110. Other bonding techniques are possible to connect the electronic system 121 to the pixels 150 without using the vias 131.

When radiation from the radiation source (not shown) hits the radiation absorption layer 110 including diodes, particles of the radiation may be absorbed and generate one or more charge carriers (e.g., electrons, holes) by a number of mechanisms. The charge carriers may drift to the electrodes of one of the diodes under an electric field. The electric field may be an external electric field. The electrical contact 119B may include discrete portions each of which is in electrical contact with the discrete regions 114. The term “electrical contact” may be used interchangeably with the word “electrode. ” In an embodiment, the charge carriers may drift in directions such that the charge carriers generated by a single particle of the radiation are not substantially shared by two different discrete regions 114 ( “not substantially shared” here means less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow to a different one of the discrete regions 114 than the rest of the charge carriers) . Charge carriers generated by a particle of the radiation incident around the footprint of one of these discrete regions 114 are not substantially shared with another of these discrete regions 114. A pixel 150 associated with a discrete region 114 may be an area around the discrete region 114 in which substantially all (more than 98%, more than 99.5%, more than 99.9%, or more than 99.99%of) charge carriers generated by a particle of the radiation incident therein flow to the discrete region 114. Namely, less than 2%, less than 1%, less than 0.1%, or less than 0.01%of these charge carriers flow beyond the pixel 150.

Fig. 4 schematically shows a detailed cross-sectional view of the radiation detector 100 of Fig. 1 along the line 2-2, according to an alternative embodiment. More specifically, the radiation absorption layer 110 may include a resistor of a semiconductor material such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof, but does not include a diode. The semiconductor material may have a high mass attenuation coefficient for the radiation of interest. In an embodiment, the electronics layer 120 of Fig. 4 is similar to the electronics layer 120 of Fig. 3 in terms of structure and function.

When the radiation hits the radiation absorption layer 110 including the resistor but not diodes, it may be absorbed and generate one or more charge carriers by a number of mechanisms. A particle of the radiation may generate 10 to 100,000 charge carriers. The charge carriers may drift to the

electrical contacts

119A and 119B under an electric field. The electric field may be an external electric field. The electrical contact 119B may include discrete portions. In an embodiment, the charge carriers may drift in directions such that the charge carriers generated by a single particle of the radiation are not substantially shared by two different discrete portions of the electrical contact 119B ( “not substantially shared” here means less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow to a different one of the discrete portions than the rest of the charge carriers) . Charge carriers generated by a particle of the radiation incident around the footprint of one of these discrete portions of the electrical contact 119B are not substantially shared with another of these discrete portions of the electrical contact 119B. A pixel 150 associated with a discrete portion of the electrical contact 119B may be an area around the discrete portion in which substantially all (more than 98%, more than 99.5%, more than 99.9%or more than 99.99%of) charge carriers generated by a particle of the radiation incident therein flow to the discrete portion of the electrical contact 119B. Namely, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow beyond the pixel associated with the one discrete portion of the electrical contact 119B.

RADIATION DETECTING SYSTEM AND OPERATION

Fig. 5 schematically shows a radiation detecting system 500, according to an embodiment. In an embodiment, the radiation detecting system 500 may include a main radiation detector 510Ma, a monitoring radiation detector 510Mo, a radiation source 520, and a controller 530. The monitoring radiation detector 510Mo and the main radiation detector 510Ma may be separate and distinct from each other. The monitoring radiation detector 510Mo and the main radiation detector 510Ma may be the same radiation detector. The monitoring radiation detector 510Mo may be part of the main radiation detector 510Ma or vice versa. The monitoring radiation detector 510Mo and the main radiation detector 510Ma may different portions of a same detector.

In an embodiment, one or both of the main radiation detector 510Ma and the monitoring radiation detector 510Mo may be similar to the radiation detector 100 of Fig. 1 –Fig. 4 in terms of structure and function.

In an embodiment, the radiation source 520 may send an excitation radiation beam 525e from the radiation source 520 toward an object 540. In an embodiment, the excitation radiation beam 525e may include X-rays. In an embodiment, the object 540 may generate XRF (X-ray fluorescent) radiation 545 from the object 540 toward the main radiation detector 510Ma in response to the object 540 being hit by the excitation radiation beam 525e.

In an embodiment, the radiation source 520 may also send a control radiation beam 525c from the radiation source 520 toward the monitoring radiation detector 510Mo. In an embodiment, the control radiation beam 525c may include X-rays.

In an embodiment, the monitoring radiation detector 510Mo may be stationary with respect to the radiation source 520.

In an embodiment, at any time point, the intensity of the excitation radiation beam 525e may be related to the intensity of the control radiation beam 525c. Namely, the intensity of the excitation radiation beam 525e has a known relationship with the intensity of the control radiation beam 525c. For example, at any time point, the intensity of the excitation radiation beam 525e may be 3 times the intensity of the control radiation beam 525c. In an embodiment, at any time point, the intensity of the excitation radiation beam 525e may be the same as the intensity of the control radiation beam 525c.

APPARENT INTENSITY OF XRF RADIATION

In an embodiment, an apparent intensity of the XRF radiation 545 may be determined. In an embodiment, the apparent intensity of the XRF radiation 545 may be determined by the main radiation detector 510Ma. In an embodiment, the main radiation detector 510Ma may determine the apparent intensity of the XRF radiation 545 by measuring the apparent intensity of the XRF radiation 545.

Specifically, in an embodiment, the main radiation detector 510Ma may measure the apparent intensity of the XRF radiation 545 by (A) capturing a first image of the object 540 based on the XRF radiation 545 from the object 540, then (B) determining a first sum of the values of all picture elements of the first image, and then (C) calculating the apparent intensity of the XRF radiation 545 based on the first sum.

Note that the words “first” , “second” , and other ordinal numerals in the present patent application are used only for easy reference and do not imply any chronological order.

Note that the term “image” in the present patent application is not limited to spatial distribution of a property of a radiation (such as intensity) . For example, the term “image” may also include the spatial distribution of density of a substance or element.

CONTROL INTENSITY OF CONTROL RADIATION BEAM

In an embodiment, a control intensity of the control radiation beam 525c may be determined. In an embodiment, the control intensity of the control radiation beam 525c may be determined by the monitoring radiation detector 510Mo. In an embodiment, the monitoring radiation detector 510Mo may determine the control intensity of the control radiation beam 525c by measuring the control intensity of the control radiation beam 525c.

Specifically, in an embodiment, the monitoring radiation detector 510Mo may measure the control intensity of the control radiation beam 525c by (A) capturing a second image based on the control radiation beam 525c from the radiation source 520, then (B) determining a second sum of the values of all picture elements of the second image, and then (C) calculating the control intensity of the control radiation beam 525c based on the second sum.

TIME POINTS FOR WHICH INTENSITIES ARE DETERMINED

In an embodiment, the apparent intensity of the XRF radiation 545 and the control intensity of the control radiation beam 525c may be determined for a first time point and a second time point respectively, and the first time point is temporally related to the second time point. Namely, the temporal difference between the first time point and the second time point is known. For example, the first time point may be 10 ms after the second time point.

In an embodiment, the first time point and the second time point may be the same. In other words, the apparent intensity of the XRF radiation 545 and the control intensity of the control radiation beam 525c are determined for a same time point.

NORMALIZED INTENSITY OF XRF RADIATION

In an embodiment, a normalized intensity of the XRF radiation 545 may be determined based on (A) the apparent intensity of the XRF radiation 545 and (B) the control intensity of the control radiation beam 525c. In an embodiment, the controller 530 may be electrically connected to the main radiation detector 510Ma and monitoring radiation detector 510Mo. In an embodiment, the controller 530 may determine the normalized intensity of the XRF radiation 545 based on (A) the apparent intensity of the XRF radiation 545 and (B) the control intensity of the control radiation beam 525c.

In an embodiment, the normalized intensity of the XRF radiation 545 divided by the apparent intensity of the XRF radiation 545 may be equal to a pre-determined base intensity of the control radiation beam 525c divided by the control intensity of the control radiation beam 525c.

For example, assume it is determined that the control radiation beam 525c from the radiation source 520 has a base intensity of 100 units. Assume further that the apparent intensity of the XRF radiation 545 for a particular time point as measured by the main radiation detector 510Ma is 30 units, and that the control intensity of the control radiation beam 525c for the particular time point as measured by the monitoring radiation detector 510Mo is 120 units. Then, the normalized intensity I _N of the XRF radiation 545 can be determined using the relationship described above: I _N/30 = 100/120. From this equation, the normalized intensity of the XRF radiation 545 for the particular time point can be calculated as follows: I _N = (100/120) ×30 = 25 units.

FLOWCHART GENERALIZING OPERATION OF RADIATION DETECTING SYSTEM

Fig. 6 shows a flowchart 600 generalizing the operation of the radiation detecting system 500 of Fig. 5, according to an embodiment. Specifically, in step 610a, the operation may include sending an excitation radiation beam from a radiation source toward an object thereby causing XRF (X-ray fluorescent) radiation to be sent from the object. For example, in the embodiments described above, with reference to Fig. 5, the radiation source 520 sends the excitation radiation beam 525e from the radiation source 520 toward the object 540 thereby causing the XRF radiation 545 to be sent from the object 540.

In step 610b, the operation may include determining an apparent intensity of the XRF radiation. For example, in the embodiments described above, with reference to Fig. 5, the main radiation detector 510Ma determines the apparent intensity of the XRF radiation 545.

In step 620a, the operation may include sending a control radiation beam from the radiation source. For example, in the embodiments described above, with reference to Fig. 5, the radiation source 520 sends the control radiation beam 525c from the radiation source 520 toward the monitoring radiation detector 510Mo.

In step 620b, the operation may include determining a control intensity of the control radiation beam. For example, in the embodiments described above, with reference to Fig. 5, the monitoring radiation detector 510Mo determines the control intensity of the control radiation beam 525c.

In step 630, the operation may include determining a normalized intensity of the XRF radiation based on (a) the apparent intensity of the XRF radiation and (b) the control intensity of the control radiation beam. For example, in the embodiments described above, with reference to Fig. 5, the controller 530 determines the normalized intensity of the XRF radiation 545 based on (a) the apparent intensity of the XRF radiation 545 and (b) the control intensity of the control radiation beam 525c.

OTHER EMBODIMENTS

MAIN RADIATION DETECTOR NOT FACE THE RADIATION SOURCE

In an embodiment, with reference to Fig. 5, the main radiation detector 510Ma may not receive any radiation particle from the radiation source 520. Specifically, in an embodiment, the radiation detecting system 500 may include a blocking device 550 that blocks all radiation particles from the radiation source 520 and aimed at the main radiation detector 510Ma. In an embodiment, the blocking device 550 may enclose the radiation source 520 but allow the excitation radiation beam 525e from the radiation source 520 to reach the object 540 through a window 550w as shown.

In an embodiment, the blocking device 550 may include a heavy metal such as lead. As a result, all radiation particles from the radiation source 520 and aimed at the main radiation detector 510Ma are prevented by the blocking device 550 from reaching the main radiation detector 510Ma.

RELATIVE POSITIONS OF RADIATION SOURCE, OBJECT, AND MONITORING RADIATION DETECTOR

In an embodiment, with reference to Fig. 5, the relative positions of the radiation source 520, the object 540, and the monitoring radiation detector 510Mo may be such that no radiation particle from the radiation source 520 and aimed at the object 540 hits the monitoring radiation detector 510Mo. For example, in an embodiment, no radiation particle of the excitation radiation beam 525e may hit the monitoring radiation detector 510Mo as shown in Fig. 5.

ALTERNATIVE EMBODIMENTS

ATTENUATION DEVICE FOR CONTROL RADIATION BEAM

In the embodiments described above, with reference to Fig. 5, the monitoring radiation detector 510Mo measures the control intensity of the control radiation beam 525c directly. Alternatively, with reference to Fig. 7, the monitoring radiation detector 510Mo may measure the control intensity of the control radiation beam 525c indirectly as follows.

Firstly, in an embodiment, an attenuation device 710 may attenuate the control radiation beam 525c by an attenuation ratio resulting in an attenuated control radiation beam 712. In an embodiment, the attenuation device 710 may be positioned between the radiation source 520 and the monitoring radiation detector 510Mo as shown. In an embodiment, the attenuation device 710 may include a metal thin film.

Then, in an embodiment, the monitoring radiation detector 510Mo may receive the attenuated control radiation beam 712 and measure the intensity of the attenuated control radiation beam 712.

Then, in an embodiment, the controller 530 may calculate the control intensity of the control radiation beam 525c based on (A) the intensity of the attenuated control radiation beam 712 as measured by the monitoring radiation detector 510Mo and (B) the attenuation ratio.

For example, assume the attenuation ratio is 0.5, and the intensity of the attenuated control radiation beam 712 as measured by the monitoring radiation detector 510Mo is 100 units. Then, the control intensity of the control radiation beam 525c can be calculated to be: 100 units/0.5 = 200 units.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

A system, comprising a radiation source configured to send an excitation radiation beam from the radiation source toward an object thereby causing emission of XRF (X-ray fluorescent) radiation from the object, and configured to send a control radiation beam from the radiation source,

wherein the system is configured to determine an apparent intensity of the XRF radiation, to determine a control intensity of the control radiation beam, and to determine a normalized intensity of the XRF radiation based on the apparent intensity of the XRF radiation and the control intensity of the control radiation beam.
The system of claim 1, wherein an intensity of the excitation radiation beam is related to an intensity of the control radiation beam.
The system of claim 2, wherein an intensity of the excitation radiation beam is equal to an intensity of the control radiation beam.
The system of claim 1,

wherein the apparent intensity of the XRF radiation and the control intensity of the control radiation beam are determined for a first time point and a second time point respectively, and

wherein the first time point is temporally related to the second time point.
The system of claim 4, wherein the first time point and the second time point are the same.
The system of claim 1, further comprising a main radiation detector configured to measure the apparent intensity of the XRF radiation.
The system of claim 6, wherein the main radiation detector does not receive any radiation particle from the radiation source.
The system of claim 7, further comprising a blocking device configured to prevent all radiation particles from the radiation source and aimed at the main radiation detector from reaching the main radiation detector.
The system of claim 1, further comprising a monitoring radiation detector configured to measure the control intensity of the control radiation beam.
The system of claim 9, wherein no radiation particle from the radiation source and aimed at the object hits the monitoring radiation detector.
The system of claim 9, wherein the monitoring radiation detector is stationary with respect to the radiation source.
The system of claim 1, further comprising:

an attenuation device configured to attenuate the control radiation beam by an attenuation ratio resulting in an attenuated control radiation beam;

a monitoring radiation detector configured to measure an intensity of the attenuated control radiation beam; and

a controller configured to calculate the control intensity of the control radiation beam based on (A) the intensity of the attenuated control radiation beam and (B) the attenuation ratio.
The system of claim 1, wherein the normalized intensity of the XRF radiation divided by the apparent intensity of the XRF radiation equals a pre-determined base intensity of the control radiation beam divided by the control intensity of the control radiation beam.
The system of claim 1,

wherein the excitation radiation beam comprises X-rays, and

wherein the control radiation beam comprises X-rays.
A method, comprising:

sending an excitation radiation beam from a radiation source toward an object thereby causing emission of XRF (X-ray fluorescent) radiation from the object;

sending a control radiation beam from the radiation source;

determining an apparent intensity of the XRF radiation;

determining a control intensity of the control radiation beam; and

determining a normalized intensity of the XRF radiation based on (a) the apparent intensity of the XRF radiation and (b) the control intensity of the control radiation beam.
The method of claim 15, wherein an intensity of the excitation radiation beam is related to an intensity of the control radiation beam.
The method of claim 16, wherein an intensity of the excitation radiation beam is equal to an intensity of the control radiation beam.
The method of claim 15,

wherein the apparent intensity of the XRF radiation and the control intensity of the control radiation beam are determined for a first time point and a second time point respectively, and

wherein the first time point is temporally related to the second time point.
The method of claim 18, wherein the first time point and the second time point are the same.
The method of claim 15, wherein said determining the apparent intensity of the XRF radiation comprises measuring the apparent intensity with a main radiation detector.
The method of claim 20, wherein the main radiation detector does not receive any radiation particle from the radiation source.
The method of claim 21, wherein all radiation particles from the radiation source and aimed at the main radiation detector are prevented from reaching the main radiation detector.
The method of claim 15, wherein said determining the control intensity of the control radiation beam comprises measuring the control intensity with a monitoring radiation detector.
The method of claim 23, wherein no radiation particle from the radiation source and aimed at the object hits the monitoring radiation detector.
The method of claim 23, wherein the monitoring radiation detector is stationary with respect to the radiation source.
The method of claim 15, wherein said determining the control intensity of the control radiation beam comprises:

attenuating the control radiation beam by an attenuation ratio resulting in an attenuated control radiation beam;

measuring an intensity of the attenuated control radiation beam with a monitoring radiation detector; and

calculating the control intensity of the control radiation beam based on (A) the intensity of the attenuated control radiation beam and (B) the attenuation ratio.
The method of claim 15, wherein the normalized intensity of the XRF radiation divided by the apparent intensity of the XRF radiation equals a pre-determined base intensity of the control radiation beam divided by the control intensity of the control radiation beam.
The method of claim 15,

wherein the excitation radiation beam comprises X-rays, and

wherein the control radiation beam comprises X-rays.