Scanning object with radiation detector

Abstract

A method includes scanning an object (520) with an imaging system (500) having a radiation detector (100) and a radiation source (510) that are stationary relative to each other. In the scan, for i = 1,..., M, the scan (i) is performed by translating the radiation detector (100) along the same translation plane (106) and in the direction (i), for a value of i one at a time in order. The Ox axis and the Oy axis are both located on the translation plane (106) and are perpendicular to each other. The orthogonal projection of direction (i) on the Oy axis does not point to two opposite directions. The orthogonal projection of direction (i) on the Ox axis points alternately in two opposite directions. For i = 1,..., (M-1), the direction (i) and the direction (i + 1) are not parallel to each other. Each point of the object (520) is scanned in at least two of the scans.

Description

[Background technology]

[0001] A radiation detector is a device that measures a property of radiation. Examples of such properties may include the spatial distribution of the intensity, phase, and polarization of the radiation. The radiation measured by a radiation detector may be radiation that has passed through an object. The radiation measured by a radiation detector may be electromagnetic radiation, such as infrared light, visible light, ultraviolet light, X-rays, or gamma rays. The radiation may be of other types, such as alpha rays and beta rays. An imaging system may include one or more image sensors, each of which may have one or more radiation detectors. [Summary of the invention]

[0002] A method is disclosed herein, the method comprising: scanning an object using an imaging system, the imaging system comprising a radiation detector and a radiation source that are stationary relative to each other. The scanning of the object comprises: for i=1, ..., M, sequentially one value of i at a time, performing scan (i) by (A) translating the radiation detector along the same translation plane and (B) along a direction (i). M is an integer greater than 1. The Ox axis and the Oy axis are both located in the translation plane and are perpendicular to each other. The orthogonal projections of the directions (i), i=1, ..., M on the Oy axis do not point to two opposite directions. The orthogonal projections of the directions (i), i=1, ..., M on the Ox axis alternately point to two opposite directions. For i=1, ..., (M-1), the directions (i) and the directions (i+1) are not parallel to each other. Each point of the object is scanned in at least two of the scans (i), i=1, ..., M.

[0003] In one aspect, for i=1, ..., (M-2), the direction (i) and the direction (i+2) are parallel to each other.

[0004] In one aspect, each of said points is scanned in no more than 2 of said scans (i), i=1, ...,M.

[0005] In one aspect, the translation plane (A) intersects all source-facing sensing elements of the radiation detector or (B) is a best fit plane for all source-facing sensing elements of the radiation detector.

[0006] In one aspect, at a point in time during said scan (i), i=1, ..., M, said translation plane is perpendicular to a line intersecting said radiation source and source-facing sensing elements of said radiation detector.

[0007] In one aspect, a plane of sensing elements of the radiation detector intersects the radiation source.

[0008] On the one hand, for each odd value of i, the scan (i) includes sending a radiation beam (i) in a same first energy range to the object using the radiation source, and for each even value of i, the scan (i) includes sending a radiation beam (i) in a same second energy range to the object using the radiation source, and the first energy range and the second energy range are different.

[0009] In one aspect, the first energy range and the second energy range do not overlap.

[0010] On the one hand, for each value of i, the scan (i) includes counting plus 1 using a counter of the radiation detector in response to radiation particles in a third energy range striking the radiation detector, and counting minus 1 using the counter in response to radiation particles in a fourth energy range striking the radiation detector, and the third energy range and the fourth energy range do not overlap.

[0011] In one aspect, for each value of i, the scanning (i) comprises: recording, using a first counter of the radiation detector, a number of radiation particles of a fifth energy range that strike a sensing element of the radiation detector; and recording, using a second counter of the radiation detector, a number of radiation particles of a sixth energy range that strike the sensing element. The fifth energy range and the sixth energy range do not overlap.

[0012] In one aspect, all M translation distances of the scans (i), i=1, ..., M, respectively measured in directions parallel to the Ox axis, are the same.

[0013] On the one hand, for i=1, ..., (M-1), the sum of (A) the translation distance of the scan (i) in a direction parallel to the Oy axis and (B) the translation distance of the scan (i+1) in a direction parallel to the Oy axis does not exceed the size of the radiation detector in a direction parallel to the Oy axis.

[0014] In one aspect, for i=1, ..., (M-1), one of the direction (i) and the direction (i+1) is parallel to the Ox axis.

[0015] Disclosed herein is an apparatus comprising an imaging system comprising a radiation detector and a radiation source that are stationary relative to each other. The imaging system is configured to scan an object. The imaging system scanning the object comprises: for i=1, ..., M, sequentially one value of i at a time, performing scan (i) by (A) translating the radiation detector along the same translation plane of the radiation detector and (B) along a direction (i). M is an integer greater than 1. The Ox axis and the Oy axis are both located in the translation plane and are perpendicular to each other. The orthogonal projections of the directions (i), i=1, ..., M on the Oy axis do not point to two opposite directions. The orthogonal projections of the directions (i), i=1, ..., M on the Ox axis alternately point to two opposite directions. For i=1, ..., (M-1), the directions (i) and the directions (i+1) are not parallel to each other. Each point of the object is scanned in at least two of the scans (i), i=1, ..., M.

[0016] In one aspect, for i=1, ..., (M-2), the direction (i) and the direction (i+2) are parallel to each other.

[0017] In one aspect, each of said points is scanned in no more than 2 of said scans (i), i=1, ...,M.

[0018] In one aspect, the translation plane (A) intersects all source-facing sensing elements of the radiation detector or (B) is a best fit plane for all source-facing sensing elements of the radiation detector.

[0019] In one aspect, at a point in time during said scan (i), i=1, ..., M, said translation plane is perpendicular to a line intersecting said radiation source and source-facing sensing elements of said radiation detector.

[0020] In one aspect, a plane of sensing elements of the radiation detector intersects the radiation source.

[0021] On the one hand, for each odd value of i, the scan (i) includes sending a radiation beam (i) in a same first energy range to the object using the radiation source, and for each even value of i, the scan (i) includes sending a radiation beam (i) in a same second energy range to the object using the radiation source, and the first energy range and the second energy range are different.

[0022] In one aspect, the first energy range and the second energy range do not overlap.

[0023] On the one hand, for each value of i, the scan (i) includes counting plus 1 using a counter of the radiation detector in response to radiation particles in a third energy range striking the radiation detector, and counting minus 1 using the counter in response to radiation particles in a fourth energy range striking the radiation detector, and the third energy range and the fourth energy range do not overlap.

[0024] In one aspect, for each value of i, the scanning (i) comprises: recording, using a first counter of the radiation detector, a number of radiation particles of a fifth energy range that strike a sensing element of the radiation detector; and recording, using a second counter of the radiation detector, a number of radiation particles of a sixth energy range that strike the sensing element. The fifth energy range and the sixth energy range do not overlap.

[0025] In one aspect, all M translation distances of the scans (i), i=1, ..., M, respectively measured in directions parallel to the Ox axis, are the same.

[0026] On the one hand, for i=1, ..., (M-1), the sum of (A) the translation distance of the scan (i) in a direction parallel to the Oy axis and (B) the translation distance of the scan (i+1) in a direction parallel to the Oy axis does not exceed the size of the radiation detector in a direction parallel to the Oy axis.

[0027] In one aspect, for i=1, ..., (M-1), one of the direction (i) and the direction (i+1) is parallel to the Ox axis.

Brief Description of the Drawings

[0028] Figure 1 A radiation detector according to an embodiment is schematically illustrated.

[0029] Figure 2 A simplified cross-sectional view of a radiation detector according to an embodiment is schematically shown.

[0030] Figure 3 A detailed cross-sectional view of a radiation detector according to an embodiment is schematically shown.

[0031] Figure 4 A detailed cross-sectional view of a radiation detector according to an alternative embodiment is schematically shown.

[0032] Figure 5 A perspective view of an imaging system according to an embodiment is schematically shown.

[0033] 6A to 6F The operation of an imaging system according to an embodiment is shown.

[0034] Figure 7 A flow chart outlining the operation of an imaging system according to an embodiment is shown. [Specific implementation method]

[0035] Radiation Detectors

[0036] Figure 1 A radiation detector 100 is schematically shown 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 (e.g. Figure 1 as shown), a honeycomb array, a hexagonal array, or any other suitable array. Figure 1 The array of pixels 150 in the example of FIG. 4 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.

[0037] Each pixel 150 can be configured to detect radiation from a radiation source (not shown) incident thereon, and can be configured to measure the characteristics of the radiation (e.g., the energy, wavelength, and frequency of the particles). Radiation may include radiation particles such as photons (X-rays, gamma rays, etc.) and subatomic particles (alpha particles, beta particles, etc.). Each pixel 150 can be configured to count the number of radiation particles incident thereon and whose energy falls into multiple energy bins over a period of time. All pixels 150 can be configured to count the number of radiation particles incident thereon and falling into multiple energy bins over the same period of time. When the incident radiation particles have similar energies, the pixel 150 can be configured only to count the number of radiation particles incident thereon over a period of time without measuring the energy of a single radiation particle.

[0038] Each pixel 150 may have its own analog-to-digital converter (ADC) configured to digitize an analog signal representing the energy of an incident radiation particle into a digital signal, or to digitize an analog signal representing the total energy of multiple incident radiation particles into a digital signal. Pixels 150 may be configured to operate in parallel. For example, when one pixel 150 measures an incident radiation particle, another pixel 150 may be waiting for the radiation particle to arrive. Pixels 150 may not necessarily be individually addressable.

[0039] The radiation detector 100 described herein may have applications such as X-ray telescopes, X-ray mammography, industrial X-ray defect detection, X-ray microscopy or microradiography, X-ray casting inspection, X-ray nondestructive testing, X-ray weld inspection, X-ray digital subtraction angiography, etc. It may be appropriate to use the radiation detector 100 instead of a photographic plate, photographic film, a photo-stimulated phosphor plate (PSP plate), an X-ray image intensifier, a scintillator, or other semiconductor X-ray detector.

[0040] Figure 2 Schematically shows a Figure 1 2-2. Specifically, the radiation detector 100 may include a radiation absorbing layer 110 and an electronic circuit layer 120 (which may include one or more ASICs or application specific integrated circuits) for processing and analyzing electrical signals generated in the radiation absorbing layer 110 by incident radiation. The radiation detector 100 may or may not include a scintillator (not shown). The radiation absorbing 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.

[0041] As an example, Figure 3 Schematically shows Figure 1 Detailed cross-sectional view of the radiation detector 100 along line 2-2. Specifically, the radiation absorbing layer 110 may include one or more diodes (e.g., pin or pn) formed by one or more discrete regions 114 of the first doping region 111, the second doping region 113. The second doping region 113 may be separated from the first doping region 111 by an optional intrinsic region 112. The discrete regions 114 may be separated from each other by the first doping region 111 or the intrinsic region 112. The first doping region 111 and the second doping region 113 may have opposite types of doping (e.g., the first doping region 111 is p-type and the second doping region 113 is n-type, or the first doping region 111 is n-type and the second doping region 113 is p-type). Figure 3 In the example of , each discrete region 114 of the second doped region 113 forms a diode with the first doped region 111 and the optional intrinsic region 112. That is, in Figure 3 In the example of FIG. 1 , the radiation absorbing layer 110 has a plurality of diodes (more specifically, 7 diodes corresponding to Figure 1 The array has 7 pixels in a row of 150, for simplicity, Figure 3 Only two pixels 150 are marked in FIG. 1 . The plurality of diodes may have an electrical contact 119A as a common electrode. The first doped region 111 may also have a plurality of discrete portions.

[0042] The electronic circuit layer 120 may include an electronic system 121 suitable for processing or interpreting signals generated by radiation incident on the radiation absorption layer 110. The electronic system 121 may include analog circuits such as filter networks, amplifiers, integrators, and comparators, or digital circuits such as microprocessors and memories. The electronic system 121 may include one or more analog-to-digital converters. The electronic system 121 may include components shared by multiple 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 between all pixels 150. The electronic system 121 may be electrically connected to the pixel 150 through the through hole 131. The space between the through holes may be filled with a filling material 130, which may increase the mechanical stability of the connection between the electronic circuit layer 120 and the radiation absorption layer 110. Other bonding techniques may connect the electronic system 121 to the pixel 150 without using the through hole 131.

[0043] When radiation from a radiation source (not shown) strikes the radiation absorbing layer 110 including a diode, the radiation particles may be absorbed and generate one or more carriers (e.g., electrons, holes) through a variety of mechanisms. The carriers may drift to one of the electrodes of the diodes under an electric field. The electric field may be an external electric field. The electrical contact 119B may include a plurality of discrete portions, each of which is in electrical contact with the discrete region 114. The term "electrical contact" may be used interchangeably with the term "electrode". In one embodiment, the carriers may drift in a plurality of directions, and the carriers generated by a single radiation particle are not substantially shared by two different discrete regions 114 (here "substantially not shared by..." means that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these carriers flow to a discrete region different from the discrete region to which the remaining carriers flow in the plurality of discrete regions 114). The charge carriers generated by radiation particles incident around the footprint of one of the discrete regions 114 are substantially not shared by another of the 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 the charge carriers generated by radiation particles incident therein flow toward the discrete region 114. That is, less than 2%, less than 1%, less than 0.1%, or less than 0.01% of the charge carriers flow out of the pixel 150.

[0044] Figure 4 Schematically shows a Figure 1Detailed cross-sectional view of radiation detector 100 along line 2-2. More specifically, radiation absorbing layer 110 may include resistors of semiconductor materials such as silicon, germanium, GaAs, CdTe, CdZnTe, or combinations thereof, but not diodes. The semiconductor material may have a high mass attenuation coefficient for the radiation of interest. In one embodiment, Figure 4 The electronic circuit layer 120 is similar in structure and function to Figure 3 The electronic circuit layer 120 is provided.

[0045] When radiation strikes the radiation absorbing layer 110, which includes a resistor but does not include a diode, it can be absorbed and generate one or more carriers through a variety of mechanisms. The radiation particles can generate 10 to 100,000 carriers. The carriers can drift to the electrical contacts 119A and 119B under an electric field. The electric field can be an external electric field. The electrical contact 119B may include multiple discrete portions. In one embodiment, the carriers can drift in multiple directions, and the carriers generated by a single radiation particle are substantially not shared by two different discrete portions of the electrical contact 119B (here "substantially not shared by..." means that less than 2%, less than 0.5%, less than 0.1% or less than 0.01% of these carriers flow to a discrete portion different from the discrete portion to which the remaining carriers flow). The carriers generated by the radiation particles incident on the occupied space of one of the discrete portions of the electrical contact 119B are substantially not shared by another discrete portion of the discrete portions of the electrical contact 119B. A pixel 150 associated with a discrete portion of electrical contact 119B may be a region 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 the charge carriers generated by radiation particles incident therein flow toward the discrete portion of electrical contact 119B. That is, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these charge carriers flow out of the pixel associated with the discrete portion of electrical contact 119B.

[0046] Imaging System

[0047] Figure 5 A perspective view of an imaging system 500 according to an embodiment is schematically shown. In one embodiment, the imaging system 500 may include a radiation detector 100 and a radiation source 510.

[0048] In one embodiment, the object 520 may be located between the radiation detector 100 and the radiation source 510. For example, the object 520 may be a part of a human body (eg, a thigh). In one embodiment, the imaging system 500 may be used to scan the object 520.

[0049] In one embodiment, the radiation detector 100 and the radiation source 510 may be as follows. Figure 5 The arrangement shown (referred to as a side-incident arrangement) makes the sensor element plane 104 of the radiation detector 100 intersect the radiation source 510. With respect to the sensor element plane 104, if all the sensor elements 150 of the radiation detector 100 are coplanar, the sensor element plane 104 may be a plane that actually intersects all the sensor elements 150 of the radiation detector 100. However, if all the sensor elements 150 of the radiation detector 100 are not coplanar, the sensor element plane 104 may be a best-fit plane (e.g., a least squares method) of all the sensor elements 150 of the radiation detector 100.

[0050] A radiation detector 100 is said to translate along a plane if (A) it intersects the radiation detector 100 and (B) every point of the radiation detector 100 that is on the plane at any point in time during the translation of the radiation detector 100 remains on the plane throughout the translation of the radiation detector 100.

[0051] The source-facing sensor element 150 is the sensor element 150 that faces the radiation source 510. In other words, radiation particles from the radiation source 510 can strike the source-facing sensor element 150 without being interfered by any other sensor element 150. Figure 5 In FIG. 1 , there are seven sensing elements 150 facing the source (top row).

[0052] Operation of the imaging system

[0053] In one embodiment, reference Figure 5 In general, imaging system 500 may operate as follows. Radiation source 510 may send radiation beam 512 toward object 520. Radiation beam 512 may include X-rays. In one example, radiation beam 512 is a fan beam.

[0054] In one embodiment, radiation detector 100 and radiation source 510 may be stationary relative to each other during operation of imaging system 500 .

[0055] In one embodiment, radiation detector 100 and radiation source 510 may translate along direction 102 as imaging system 500 scans object 520. In other words, radiation detector 100 captures multiple images of object 520 as radiation detector 100 and radiation source 510 translate along direction 102.

[0056] The term "image" in this patent application (including claims) is not limited to the spatial distribution of a property (eg, intensity) of radiation. For example, the term "image" may also include the spatial distribution of the density of a substance or element.

[0057] In one embodiment, direction 102 may be selected such that radiation detector 100 translates along translation plane 106, such as Figure 5 In one embodiment, the translation plane 106 along which the radiation detector 100 is translated may (A) intersect all source-facing sensing elements 150 of the radiation detector 100 , or (B) be a best fit plane for all source-facing sensing elements 150 of the radiation detector 100 .

[0058] Furthermore, in one embodiment, the translation plane 106 along which the radiation detector 100 translates may be perpendicular to the line 108, which intersects the radiation source 510 and the source-facing sensing element 150 (at point X) at a point in time during the translation of the radiation detector 100.

[0059] Zigzag Scan

[0060] 6A to 6F The operation of the imaging system 500 is illustrated when the imaging system 500 performs 6 scans of the object 520 according to an embodiment. Note that 6A to 6F 5 shows a top view of the radiation detector 100 and the object 520 as viewed from the radiation source 510. For simplicity, the object 520 is only shown in FIG. Fig. 6A and Fig. 6F is shown in (i.e., not in FIG. 6B to FIG. 6E ).

[0061] Specifically, in one embodiment, reference Fig. 6A During the first scan, radiation detector 100 may be translated along translation plane 106 and along direction 102A from position S to position A. Note that if imaging system 500 scans an area of ​​translation plane 106 only once, the area appears brighter (A), and if imaging system 500 scans the area at least twice, the area appears darker (B).

[0062] Next, in one embodiment, reference Figure 6B During the second scan, radiation detector 100 may be translated from position A to position B along translation plane 106 and along direction 102B.

[0063] Next, in one embodiment, reference Figure 6C During the third scan, the radiation detector 100 may be translated from position B to position C along the translation plane 106 and along the direction 102C.

[0064] Next, in one embodiment, reference Fig.6D During the fourth scan, the radiation detector 100 may be translated along the translation plane 106 and along the direction 102D from position C to position D.

[0065] Next, in one embodiment, reference Fig. 6E During the fifth scan, the radiation detector 100 may be translated from position D to position E along the translation plane 106 and along the direction 102E.

[0066] Next, in one embodiment, reference Fig. 6F During the sixth scan, the radiation detector 100 may be translated from position E to position F along the translation plane 106 and along the direction 102F.

[0067] In one embodiment, the Ox axis and the Oy axis may be defined such that the Ox axis and the Oy axis are located in the translation plane 106 and are perpendicular to each other, such as 6A to 6F shown.

[0068] In one embodiment, reference 6A to 6F , the six orthogonal projections of the six directions 102A, 102B, 102C, 102D, 102E, and 102F on the Oy axis may not point to two opposite directions. 6A to 6F In the figure, all six orthogonal projections of the six directions 102A, 102B, 102C, 102D, 102E, and 102F on the Oy axis point downward.

[0069] In one embodiment, reference 6A to 6F , the six orthogonal projections of the six directions 102A, 102B, 102C, 102D, 102E, and 102F on the Ox axis can point alternately to two opposite directions. Fig. 6A In FIG. 1 , the orthogonal projection of direction 102A on the Ox axis points to the right. Figure 6B In FIG. 1 , the orthogonal projection of direction 102B on the Ox axis points to the left. Figure 6C In FIG. 1 , the orthogonal projection of direction 102C on the Ox axis points to the right. Fig.6D In FIG. 1 , the orthogonal projection of direction 102D on the Ox axis points to the left. Fig. 6E In FIG. 1 , the orthogonal projection of direction 102E on the Ox axis points to the right. Fig. 6F In other words, the six orthogonal projections of the six directions 102A, 102B, 102C, 102D, 102E, and 102F on the Ox axis point to the left side alternately (ie, two opposite directions).

[0070] In one embodiment, for any two consecutive scans among the six scans, the two corresponding directions 102 may not be parallel to each other. For example, for the first scan and the second scan, the two corresponding directions 102A and 102B are not parallel to each other. For another example, for the second scan and the third scan, the two corresponding directions 102B and 102C are not parallel to each other.

[0071] In one embodiment, reference 6A to 6F , each point of the object 520 can be scanned in at least two of the first scan, the second scan, the third scan, the fourth scan, the fifth scan, and the sixth scan (i.e., the imaging system 500 scans at least twice). Assume that the object 520 is a human thigh. Then, for each point of the human thigh, data from the at least two scans can be used to determine the bone density at each point of the human thigh (referred to as bone densitometry).

[0072] Flowchart outlining the operation of the imaging system

[0073] Figure 7 Flowchart 700 outlining the operation of imaging system 500 according to an embodiment is shown. In step 710, the operation may include scanning an object using an imaging system including a radiation detector and a radiation source that are stationary relative to each other. For example, in the above embodiment, reference Figure 5 The imaging system 500 scans an object 520, and the imaging system 500 includes a radiation detector 100 and a radiation source 510 that are stationary relative to each other.

[0074] Additionally, in step 710, scanning the object includes, for i=1, ..., M, sequentially one value of i at a time, performing a scan (i) by (A) translating the radiation detector along the same translation plane and (B) along a direction (i), where M is an integer greater than 1. For example, in the above embodiment, reference Figures 5 to 6F , for i=1, ..., 6, sequentially one value of i at a time, the scan (i) is performed by translating the radiation detector 100 (A) along the same translation plane 106 and (B) along the direction (i), where M=6. Specifically, for example, referring to Fig. 6A , for i=1, scan (1) (ie, the first scan) includes translating radiation detector 100 (A) along translation plane 106 and (B) along direction 102A.

[0075] In addition, in step 710, the Ox axis and the Oy axis are both located in the translation plane and are perpendicular to each other. Direction (i), i=1, ..., the orthogonal projection of M on the Oy axis does not point to two opposite directions. For example, in the above embodiment, reference Figures 5 to 6F , the Ox axis and the Oy axis are both located in the translation plane 106 and are perpendicular to each other. In addition, all orthographic projections of the directions 102A, 102B, 102C, 102D, 102E, and 102F on the Oy axis point downward.

[0076] In addition, in step 710, the orthogonal projections of directions (i), i=1, ..., M on the Ox axis are alternately directed to two opposite directions. Figures 5 to 6F , the orthogonal projections of directions 102A, 102B, 102C, 102D, 102E, and 102F on the Ox axis point alternately to the left and right (ie, 2 opposite directions).

[0077] In addition, in step 710, for i=1, ..., (M-1), direction (i) and direction (i+1) are not parallel to each other. Figures 5 to 6F For any two consecutive scans in the six scans, the two corresponding directions 102 are not parallel to each other. Specifically, for example, direction 102A ( Fig. 6A ) and direction 102B( Figure 6B ) are not parallel to each other. Similarly, direction 102B ( Figure 6B ) and Direction 102C( Figure 6C ) are not parallel to each other, and so on.

[0078] In addition, in step 710, each point of the object is scanned in at least two scans in scan (i), i=1, ..., M. For example, in the above embodiment, referring to Fig. 6F , each point of the object 520 is scanned in at least two scans among the first scan, the second scan, the third scan, the fourth scan, the fifth scan, and the sixth scan.

[0079] Other embodiments

[0080] Scanned exactly twice

[0081] In the above embodiments, reference Figures 5 to 6F , each point of object 520 is scanned at least twice by imaging system 500. In one embodiment, each point of object 520 is scanned no more than twice by imaging system 500. In other words, each point of object 520 is scanned exactly twice by imaging system 500, such as 6A to 6F shown.

[0082] Alternating energy range for zigzag scanning

[0083] In one embodiment, reference Fig. 6ADuring the first scan, the radiation source 510 may send a first radiation beam (as part of the radiation beam 512) of a first energy range to the object 520. In other words, each radiation particle of the first radiation beam has energy within the first energy range. The first radiation beam may be used by the radiation detector 100 to perform the first scan.

[0084] Similarly, in one embodiment, reference Figure 6C During the third scan, the radiation source 510 may transmit a third radiation beam (as a portion of the radiation beam 512) of the first energy range to the object 520. The third radiation beam may be used by the radiation detector 100 to perform the third scan.

[0085] Similarly, in one embodiment, reference Fig. 6E During the fifth scan, the radiation source 510 may transmit a fifth radiation beam (as a portion of the radiation beam 512) of the first energy range to the object 520. The fifth radiation beam may be used by the radiation detector 100 to perform the fifth scan.

[0086] In one embodiment, reference Figure 6B During the second scan, the radiation source 510 may send a second radiation beam (as part of the radiation beam 512) of a second energy range to the object 520. In other words, each radiation particle of the second radiation beam has energy within the second energy range. The second radiation beam may be used by the radiation detector 100 to perform the second scan.

[0087] Similarly, in one embodiment, reference Fig.6D During the fourth scan, the radiation source 510 may transmit a fourth radiation beam (as a portion of the radiation beam 512) of the second energy range to the object 520. The fourth radiation beam may be used by the radiation detector 100 to perform the fourth scan.

[0088] Similarly, in one embodiment, reference Fig. 6F During the sixth scan, the radiation source 510 may transmit a sixth radiation beam (as a portion of the radiation beam 512) of the second energy range to the object 520. The sixth radiation beam may be used by the radiation detector 100 to perform the sixth scan.

[0089] In one embodiment, the first energy range and the second energy range may be different. In one embodiment, the first energy range and the second energy range may not overlap.

[0090] Bidirectional counter for each sensing element of the radiation detector

[0091] In one embodiment, reference Figures 1 to 5, the electronic circuit layer 120 of the radiation detector 100 may include a counter (not shown) for each sensing element 150 of the radiation detector 100 .

[0092] In one embodiment, if radiation particles of the third energy range strike each of the sensor elements 150, the counter of each of the sensor elements may count up by 1 (i.e., its count increases by 1); if radiation particles of the fourth energy range strike each of the sensor elements 150, the counter of each of the sensor elements may count down by 1 (i.e., its count decreases by 1), and the third energy range and the fourth energy range do not overlap. Please note that the counter of each of the sensor elements 150 of the radiation detector 100 is a bidirectional counter.

[0093] Two counters per sensing element

[0094] In one embodiment, reference Figures 1 to 5 , the electronic circuit layer 120 of the radiation detector 100 may include a first counter (not shown) and a second counter (not shown) for each sensing element 150 of the radiation detector 100. In one embodiment, the first counter of each sensing element 150 may record the number of radiation particles in the fifth energy range that strikes each sensing element 150; the second counter of each sensing element 150 may record the number of radiation particles in the sixth energy range that strikes each sensing element 150, and the fifth energy range does not overlap with the sixth energy range.

[0095] The translation distance on the Ox axis is the same

[0096] In one embodiment, reference 6A to 6F , (A) The first scan measured in the direction parallel to the Ox axis ( Fig. 6A ) of the translation distance (i.e., distance 102Ax), (B) of the second scan measured in a direction parallel to the Ox axis ( Figure 6B ) translation distance (not shown), (C) the third scan measured in a direction parallel to the Ox axis ( Figure 6C ) translation distance (not shown), (D) the fourth scan measured in a direction parallel to the Ox axis ( Fig.6D ) translation distance (not shown), (E) the fifth scan measured in a direction parallel to the Ox axis ( Fig. 6E ) of the translation distance (not shown) and (F) the sixth scan ( Fig. 6F ) can be the same. In other words, the 6 horizontal translation distances of the 6 scans are the same. Please note that for simplicity (i.e., the other 5 horizontal translation distances are not shown), only Fig. 6AA first horizontal translation distance (ie, distance 102Ax) is shown in FIG.

[0097] The sum of 2 consecutive vertical translation distances

[0098] In one embodiment, reference Figure 6B , the sum of (A) the translation distance of the first scan in a direction parallel to the Oy axis (i.e., distance 102Ay) and (B) the translation distance of the second scan in a direction parallel to the Oy axis (i.e., distance 102By) may not exceed the dimension of the radiation detector 100 in a direction parallel to the Oy axis (i.e., dimension 100y).

[0099] In general, the above embodiments can be expressed as follows: the sum of (A) the translation distance of scan (i) in the direction parallel to the Oy axis and (B) the translation distance of scan (i+1) in the direction parallel to the Oy axis may not exceed the size of the radiation detector 100 in the direction parallel to the Oy axis (i=1, 2, 3, 4, 5).

[0100] Special case - horizontal translation

[0101] In one embodiment, reference 6A to 6F , for any two consecutive scans, one of the two corresponding translation directions 102 may be parallel to the Ox axis. Fig. 6A and Figure 6B , one of the two directions 102A and 102B may be parallel to the Ox axis. Specifically, for example, direction 102A may point to the southeast, and direction 102B may point to the west (i.e., parallel to the Ox axis). In this particular example, reference Figure 6B , the distance 102Ay is equal to the dimension 100y, and the distance 100By is zero.

[0102] More information about translation direction

[0103] In one embodiment, reference 6A to 6F and Figure 7 In step 710, for i=1, ..., (M-2), direction (i) and direction (i+2) may be parallel to each other. For example, direction 102A and direction 102C are parallel to each other. For another example, direction 102B and direction 102D are parallel to each other.

[0104] Although 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 appended claims.

Claims

1. A method comprising: Scanning an object using an imaging system, the imaging system comprising a radiation detector and a radiation source that are stationary relative to each other, wherein scanning the object comprises: For i=1, ..., M, scanning (i) is performed by translating the radiation detector (A) along the same translation plane and (B) along direction (i), sequentially one value of i at a time, wherein M is an integer greater than 1, Wherein, the Ox axis and the Oy axis are both located in the translation plane and are perpendicular to each other. wherein the orthogonal projections of the directions (i), i=1, ..., M on the Oy axis do not point to two opposite directions, Wherein, the orthogonal projections of the directions (i), i=1, ..., M on the Ox axis point alternately to two opposite directions, Wherein, for i=1, ..., (M-1), the direction (i) and the direction (i+1) are not parallel to each other, and Each point of the object is scanned in at least two of the scans (i), i=1, ..., M.

2. The method according to claim 1, wherein: For i=1, ..., (M-2), the direction (i) and the direction (i+2) are parallel to each other.

3. The method according to claim 1, wherein: Each of the points is scanned in no more than 2 scans in the scans (i), i=1,...,M.

4. The method according to claim 1, wherein: The translation plane (A) intersects all source-facing sensing elements of the radiation detector or (B) is a best-fit plane for all source-facing sensing elements of the radiation detector.

5. The method according to claim 4, wherein: At a point in time during said scan (i), i=1, ..., M, said translation plane is perpendicular to a line intersecting said radiation source and source-facing sensing elements of said radiation detector.

6. The method according to claim 1, wherein: A plane of sensing elements of the radiation detector intersects the radiation source.

7. The method according to claim 1, in, For each odd value of i, the scanning (i) comprises sending a radiation beam (i) of the same first energy range to the object using the radiation source, wherein, for each even value of i, the scanning (i) comprises sending, by the radiation source, a radiation beam (i) of the same second energy range to the object, The first energy range and the second energy range are different.

8. The method according to claim 7, wherein: The first energy range and the second energy range do not overlap.

9. The method according to claim 1, in, For each value of i, the scanning (i) comprises counting up by one using a counter of the radiation detector in response to radiation particles of a third energy range striking the radiation detector, and counting down by one using the counter in response to radiation particles of a fourth energy range striking the radiation detector, Wherein, the third energy range and the fourth energy range do not overlap.

10. The method according to claim 1, wherein: For each value of i, the scan(i) comprises: recording, with a first counter of the radiation detector, a number of radiation particles of a fifth energy range that strike a sensing element of the radiation detector; and recording, with a second counter of the radiation detector, the number of radiation particles of a sixth energy range that strike the sensing element, and Wherein, the fifth energy range and the sixth energy range do not overlap.

11. The method according to claim 1, wherein: All M translation distances of the scans (i), i=1, ..., M, respectively measured in directions parallel to the Ox axis, are the same.

12. The method according to claim 11, wherein: For i=1, ..., (M-1), the sum of (A) the translation distance of the scan (i) in the direction parallel to the Oy axis and (B) the translation distance of the scan (i+1) in the direction parallel to the Oy axis does not exceed the size of the radiation detector in the direction parallel to the Oy axis.

13. The method according to claim 12, wherein: For i=1, ..., (M-1), one of the direction (i) and the direction (i+1) is parallel to the Ox axis.

14. An apparatus comprising an imaging system comprising a radiation detector and a radiation source that are stationary relative to each other, in, The imaging system is configured to scan an object, Wherein, the imaging system scanning the object comprises: For i=1, ..., M, scanning (i) is performed by translating the radiation detector (A) along the same translation plane of the radiation detector and (B) along direction (i), one value of i at a time in sequence, wherein M is an integer greater than 1, Wherein, the Ox axis and the Oy axis are both located in the translation plane and are perpendicular to each other. wherein the orthogonal projections of the directions (i), i=1, ..., M on the Oy axis do not point to two opposite directions, Wherein, the orthogonal projections of the directions (i), i=1, ..., M on the Ox axis point alternately to two opposite directions, Wherein, for i=1, ..., (M-1), the direction (i) and the direction (i+1) are not parallel to each other, and Each point of the object is scanned in at least two of the scans (i), i=1, ..., M.

15. The device according to claim 14, wherein: For i=1, ..., (M-2), the direction (i) and the direction (i+2) are parallel to each other.

16. The device according to claim 14, wherein: Each of the points is scanned in no more than 2 scans in the scans (i), i=1,...,M.

17. The device according to claim 14, wherein: The translation plane (A) intersects all source-facing sensing elements of the radiation detector or (B) is a best-fit plane for all source-facing sensing elements of the radiation detector.

18. The device according to claim 17, wherein: At a point in time during said scan (i), i=1, ..., M, said translation plane is perpendicular to a line intersecting said radiation source and source-facing sensing elements of said radiation detector.

19. The device according to claim 14, wherein: A plane of sensing elements of the radiation detector intersects the radiation source.

20. The device according to claim 14, in, For each odd value of i, the scanning (i) comprises sending a radiation beam (i) of the same first energy range to the object using the radiation source, wherein, for each even value of i, the scanning (i) comprises sending, by the radiation source, a radiation beam (i) of the same second energy range to the object, The first energy range and the second energy range are different.

21. The device according to claim 20, wherein: The first energy range and the second energy range do not overlap.

22. The device according to claim 14, in, For each value of i, the scanning (i) comprises counting up by one using a counter of the radiation detector in response to radiation particles of a third energy range striking the radiation detector, and counting down by one using the counter in response to radiation particles of a fourth energy range striking the radiation detector, Wherein, the third energy range and the fourth energy range do not overlap.

23. The device according to claim 14, wherein: For each value of i, the scan(i) comprises: recording, with a first counter of the radiation detector, a number of radiation particles of a fifth energy range that strike a sensing element of the radiation detector; and recording, with a second counter of the radiation detector, the number of radiation particles of a sixth energy range that strike the sensing element, and Wherein, the fifth energy range and the sixth energy range do not overlap.

24. The device according to claim 14, wherein: All M translation distances of the scans (i), i=1, ..., M, respectively measured in directions parallel to the Ox axis, are the same.

25. The device according to claim 24, wherein: For i=1, ..., (M-1), the sum of (A) the translation distance of the scan (i) in the direction parallel to the Oy axis and (B) the translation distance of the scan (i+1) in the direction parallel to the Oy axis does not exceed the size of the radiation detector in the direction parallel to the Oy axis.

26. The device according to claim 25, wherein For i=1, ..., (M-1), one of the direction (i) and the direction (i+1) is parallel to the Ox axis.

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