System and method for three-dimensional imaging

Abstract

Disclosed herein is a method comprising introducing a tracer into a body region of a living organism at an introduction site; causing emission of characteristic X-rays of the tracer in the body region (710); taking an image of the tracer in the body region with the characteristic X-rays (720); determining a first three-dimensional (3D) distribution of the tracer in the body region based on the image (730); and examining the first 3D distribution of the tracer in the body region to identify a sentinel lymph node of the introduction site. If the sentinel lymph node is not identified in the first 3D distribution, the method further comprises repeating the foregoing causing emission of characteristic X-rays of the tracer in the body region, the foregoing taking an image of the tracer in the body region, and the foregoing determining a 3D distribution of the tracer in the body region to produce a second 3D distribution of the tracer in the body region; and examining the second 3D distribution to identify the sentinel lymph node.

Description

TECHNICAL FIELD

[0002] The disclosure herein relates to three-dimensional imaging. BACKGROUND

[0004] X-ray fluorescence (XRF) is the emission of characteristic X-rays from a material that has been excited by an incident X-ray or gamma ray. Specifically, if an atom is exposed to an X-ray or gamma ray with a photon energy greater than the electron's ionization energy, an electron in an inner orbital of the atom can be ejected, leaving a vacancy in the inner orbital. When an electron in an outer orbital of the atom relaxes to fill the vacancy in the inner orbital, an X-ray (called a fluorescent X-ray photon, secondary X-ray photon, or characteristic X-ray photon) is emitted. The energy of the emitted X-ray photon is equal to the energy difference between the outer and inner orbital electrons.

[0005] For a given atom, the number of possible relaxations is finite. As shown in Figure 1A When an electron in an L orbital relaxes to fill a vacancy in a K orbital (L→K), the characteristic X-ray is called Kα. The characteristic X-ray from an M→K relaxation is called Kβ. As shown in Figure 1B The characteristic X-ray from an M→L relaxation is called Lα, and so on. SUMMARY

[0007] A method is disclosed herein, comprising introducing a tracer into a body region of a living organism at an introduction site; causing emission of characteristic X-rays of the tracer in the body region; taking images of the tracer in the body region with the characteristic X-rays using a plurality of X-ray detectors located at different positions relative to the body region; determining a first three-dimensional distribution of the tracer in the body region based on the images; and examining the first three-dimensional distribution of the tracer in the body region to identify a sentinel lymph node of the introduction site.

[0008] According to an embodiment, the method further comprises, in response to the sentinel lymph node not being identified in the first three-dimensional distribution: repeating the causing emission of characteristic X-rays of the tracer in the body region, the taking images of the tracer in the body region, and the determining a three-dimensional distribution of the tracer in the body region to produce a second three-dimensional distribution of the tracer in the body region; and examining the second three-dimensional distribution of the tracer in the body region to identify the sentinel lymph node.

[0009] According to an embodiment, the method further comprises, in response to the sentinel lymph node not being identified in the second three-dimensional distribution: repeating the causing of the emission of characteristic X-rays of the tracer in the body region, the taking of the image of the tracer in the body region, and the determining of the three-dimensional distribution of the tracer in the body region, thereby generating a third three-dimensional distribution of the tracer in the body region; and examining the third three-dimensional distribution of the tracer in the body region to identify the sentinel lymph node.

[0010] According to an embodiment, the introduction site is located within a malignant region of the organism.

[0011] According to an embodiment, the organism is a human body.

[0012] According to an embodiment, the method further comprises, in response to the sentinel lymph node being identified: removing a sample from the sentinel lymph node; and testing the sample for cancer.

[0013] According to an embodiment, the method further comprises removing additional lymph nodes surrounding the sentinel lymph node in response to cancer found in the sample as a result of the testing.

[0014] According to an embodiment, the causing of the emission of characteristic X-rays of the tracer in the body region comprises illuminating the body region with excitation radiation.

[0015] According to an embodiment, the excitation radiation comprises X-rays or gamma rays.

[0016] According to an embodiment, the tracer is non-radioactive.

[0017] Disclosed herein is a method comprising: introducing a tracer into a body region of an organism at an introduction site of the organism, wherein the body region comprises L imaging regions R i , i = 1,..., L, and wherein L is an integer greater than 1; for i = 1,..., L, causing the tracer to emit characteristic X-ray photons P i substantially only in the imaging region R i ; for i = 1,..., L, taking a region image I i of the tracer having the characteristic X-ray photons P i substantially only in the imaging region R i ; based on the region images I i , i = 1,..., L, determining a first three-dimensional distribution of the tracer in the body region; and examining the first three-dimensional distribution of the tracer in the body region to identify a sentinel lymph node of the introduction site.

[0018] According to an embodiment, the method further comprises, in response to the sentinel lymph node not being identified in the first three-dimensional distribution: repeating the causing of the emission of the characteristic X-rays from the tracer in the body region, the taking of the image of the tracer in the body region, and the determining of the three-dimensional distribution of the tracer in the body region, thereby producing a second three-dimensional distribution of the tracer in the body region; and examining the second three-dimensional distribution of the tracer in the body region to identify the sentinel lymph node.

[0019] According to an embodiment, the method further comprises, in response to the sentinel lymph node not being identified in the second three-dimensional distribution: repeating the causing of the emission of the characteristic X-rays from the tracer in the body region, the taking of the image of the tracer in the body region, and the determining of the three-dimensional distribution of the tracer in the body region, thereby producing a third three-dimensional distribution of the tracer in the body region; and examining the third three-dimensional distribution of the tracer in the body region to identify the sentinel lymph node.

[0020] According to an embodiment, the introduction site is located within a malignant region of the living body.

[0021] According to an embodiment, the living body is a human body.

[0022] According to an embodiment, the method further comprises, in response to the sentinel lymph node being identified: removing a sample from the sentinel lymph node; and testing the sample for cancer.

[0023] According to an embodiment, the method further comprises, in response to cancer being found in the sample as a result of the testing: removing additional lymph nodes surrounding the sentinel lymph node.

[0024] According to an embodiment, the causing of the emission of the characteristic X-ray photons P i from the tracer substantially only in the imaging region R i comprises illuminating the imaging region R i with excitation radiation.

[0025] According to an embodiment, the excitation radiation comprises X-rays or gamma rays.

[0026] According to an embodiment, the tracer is non-radioactive.

[0027] Disclosed herein is a method comprising: introducing a tracer into a body region of an organism at an introduction site of the organism; causing emission of characteristic X-rays of the tracer in the body region; taking an image of the tracer in the body region with the characteristic X-rays using a plurality of X-ray detectors located at different positions relative to the body region; determining a three-dimensional distribution of the tracer in the body region based on the image; repeating the foregoing causing emission of characteristic X-rays of the tracer in the body region, the taking an image of the tracer in the body region, and the determining a three-dimensional distribution of the tracer in the body region P times, thereby generating a total of P+1 three-dimensional distributions of the tracer in the body region, P being a positive integer; and examining at least one of the P+1 three-dimensional distributions of the tracer in the body region to identify at least one sentinel lymph node of the introduction site.

[0028] Disclosed herein is a method comprising: introducing a tracer into a body region of an organism at an introduction site of the organism, wherein the body region comprises L imaging regions R i , i = 1,..., L, and wherein L is an integer greater than 1; causing, for i = 1,..., L, the tracer to emit characteristic X-ray photons P i substantially only in the imaging region R i ; taking, for i = 1,..., L, a region image I i of the tracer with the characteristic X-ray photons P i substantially only in the imaging region R i ; determining, based on the region images I i , i = 1,..., L, a three-dimensional distribution of the tracer in the body region; repeating the foregoing causing, for i = 1,..., L, the tracer to emit characteristic X-ray photons P i substantially only in the imaging region R i ; the taking, for i = 1,..., L, a region image I i of the tracer with the characteristic X-ray photons P i substantially only in the imaging region R i ; the determining, based on the region images I i , i = 1,..., L, a three-dimensional distribution of the tracer in the body region Q times, thereby generating a total of Q+1 three-dimensional distributions of the tracer in the body region, Q being a positive integer; and examining at least one of the Q+1 three-dimensional distributions of the tracer in the body region to identify at least one sentinel lymph node of the introduction site. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1A and Figure 1B A mechanism of X-ray fluorescence is schematically illustrated.

[0031] Figure 2 A system according to an embodiment is schematically illustrated.

[0032] Figure 3 A side view of the system according to an embodiment is schematically illustrated.

[0033] Figure 4 A top view of an X-ray detector of the system according to an embodiment is schematically illustrated.

[0034] Figure 5 A simplified cross-sectional view of the X-ray detector according to an embodiment is schematically illustrated.

[0035] Figure 6 The system according to an embodiment can comprise a collimator.

[0036] Figure 7 A flowchart of a first imaging method according to an embodiment is illustrated.

[0037] Figure 8A A second imaging method according to an embodiment is illustrated.

[0038] Figure 8B A third imaging method according to an embodiment is illustrated.

[0039] Figure 8C A flowchart summarizing and generalizing the second and third imaging methods is illustrated.

[0040] Figure 9 A method of using the first, second and third imaging methods to help identify one or more sentinel lymph nodes according to an embodiment is illustrated. DETAILED DESCRIPTION

[0042] Figure 2 A system 200 according to an embodiment is schematically illustrated. The system 200 can comprise a plurality of X-ray detectors 102. The X-ray detectors 102 can be located at different positions relative to an object 104. For example, in the case that the object 104 is a thyroid of a human body, the X-ray detectors 102 can be arranged at different positions along a semicircle around the neck of the human body or along the length of the neck of the human body.

[0043] The X-ray detectors 102 can be arranged at approximately the same distance or at different distances from the object 104. Other suitable arrangements of the X-ray detectors 102 are possible. The X-ray detectors 102 can be equally or unequally spaced apart in the direction of the angle. The positions of the X-ray detectors 102 are not necessarily fixed. For example, each of the X-ray detectors 102 can be moved towards and away from the object 104, or can be rotated relative to the object 104.

[0044] Figure 3 The system 200 according to embodiments is schematically shown to comprise a radiation source 106. The system 200 can comprise more than one radiation source. The radiation source 106 irradiates the object 104 with radiation, which can cause a tracer (e.g., a chemical element) in the object 104 to emit characteristic X-rays (e.g., by fluorescence). The tracer can not be radioactive. The radiation from the radiation source 106 can be X-rays or gamma rays. The energy of the radiation particles can be in the range of 30-40 keV. The radiation source 106 can be movable or fixed relative to the object 104. The X-ray detectors 102 form an image of the object 104 (or more specifically, of the tracer in the object 104) using the characteristic X-rays (e.g., by detecting the intensity distribution of the characteristic X-rays). The X-ray detectors 102 can be arranged at different positions around the object 104 at which the X-ray detectors 102 do not receive radiation from the radiation source 106 that has not been scattered by the object 104. As shown, the X-ray detectors 102 can avoid those positions that would receive radiation from the radiation source 106 that has passed through the object 104. The X-ray detectors 102 can be movable or fixed relative to the object 104. Figure 3

[0045] ​In an embodiment, the object 104 may be a human body or a part of a human body (e.g., a thyroid gland). In one example, the object 104 may be the thyroid gland of a human body. In this example, the tracer may be non-radioactive iodine. The non-radioactive iodine may be introduced into the human body. Specifically, the person may be instructed to orally or by injection of a substance containing non-radioactive iodine. The non-radioactive iodine is absorbed by the thyroid gland of the human body. When radiation from the radiation source 106 is directed at the thyroid gland, the non-radioactive iodine within the thyroid gland is excited by the radiation and emits characteristic X-rays of iodine. The characteristic X-rays of iodine may include the K-line or the K-line and L-line. The X-ray detector 102 uses the characteristic X-rays of iodine to image the thyroid gland. In an embodiment, the X-ray detector 102 may be configured to ignore X-rays whose photon energy differs from the photon energy of the characteristic X-rays of iodine. The spatial distribution (e.g., three-dimensional) of the iodine in the thyroid gland may be determined based on these images. For example, the system 200 may have a processor 130 configured to determine the three-dimensional distribution of the iodine in the thyroid gland based on these captured images.

[0046] Figure 4 The diagram illustrates a top view of an X-ray detector 102 according to an embodiment. The X-ray detector 102 has an array of sensing elements 150 (also referred to as pixels 150). The array of sensing elements 150 can be a rectangular array, a cellular array, a hexagonal array, or any other suitable array. Each sensing element 150 is configured to count the number of photons of X-rays (e.g., characteristic X-rays of iodine) incident on the sensing element 150 over a period of time. The sensing elements 150 can be configured to operate in parallel. For example, while one sensing element 150 is measuring incident X-ray photons, another sensing element 150 may be waiting for the arrival of X-ray photons.

[0047] The sensing element 150 need not be individually addressable. Each X-ray detector 102 can be configured to count the number of X-ray photons within the same time period. Each sensing element 150 is capable of measuring its dark current, for example, before or simultaneously with receiving each X-ray photon. Each sensing element 150 can be configured to subtract the contribution of the dark current from the energy of the X-ray photons incident upon it.

[0048] Figure 5 A simplified cross-sectional view of an X-ray detector 102 according to an embodiment is shown. The X-ray detector 102 may include an X-ray absorbing layer 110 configured to generate an electrical signal in response to X-rays incident thereon. In an embodiment, the X-ray absorbing layer 110 may include the sensing element 150 (… Figure 4). In embodiments, the X-ray detector 102 does not include a scintillator. The X-ray absorption layer 110 can include a semiconductor material, such as silicon, germanium, gallium arsenide (GaAs), cadmium telluride (CdTe), cadmium zinc telluride (CdZnTe), or a combination thereof.

[0049] The X-ray detector 102 can include an electronics layer 120 for processing or analyzing the electrical signals generated in the X-ray absorption layer 110 by the incident X-ray photons. The electronics layer 120 can be integrated into the same chip as the X-ray absorption layer 110. Alternatively, the electronics layer 120 can be built on a separate semiconductor wafer from the X-ray absorption layer 110 and bonded to the X-ray absorption layer 110.

[0050] Figure 6 The system 200 according to embodiments is shown to include a collimator 108. For simplicity, only one X-ray detector 102 is shown. The collimator 108 can be positioned between the object 104 and the X-ray detector 102. The collimator 108 can be configured to limit the field of view of the sensing elements 150 of the X-ray detector 102. For example, the collimator 108 can only allow X-rays having a certain angle of incidence to reach the sensing elements 150. The range of the angle of incidence can be < 0.04 sr, or < 0.01 sr.

[0051] The collimator 108 can be fixed on the X-ray detector 102 or separate from the X-ray detector 102. There can be a gap between the collimator 108 and the X-ray detector 102. The collimator 108 can be movable or fixed relative to the X-ray detector 102. The system 200 can include more than one collimator 108 (e.g., one collimator 108 per X-ray detector 102).

[0052] Figure 7 A flowchart summarizing and generalizing the first imaging method according to some of the above embodiments is shown. In step 710, the emission of characteristic X-rays of the tracer in the object 104 is caused. For example, the emission of the characteristic X-rays can be caused by irradiating the object 104 with radiation having a sufficiently high energy. The radiation can be X-rays or gamma rays. In step 720, images of the tracer in the object 104 can be taken with the emitted characteristic X-rays. For example, X-ray detectors 102 located at different positions relative to the object 104 can be used to take these images. In step 730, a three-dimensional distribution of the tracer in the object 104 can be determined based on the taken images. The step 730 can be performed using the processor 130.

[0053] Figure 8A A second imaging method for taking a three-dimensional distribution (also referred to as a three-dimensional image) of the tracer in the object 104 is schematically shown according to an embodiment. In an embodiment, the system 200 for the second imaging method can include the processor 130, the radiation source 106, the collimator 108, and the X-ray detector 102. In Figure 8A and Figure 8B In the embodiments, the object 104 can have the shape of a rectangular box for simplicity of illustration. In general, the object 104 can have any shape.

[0054] In an example, the object 104 can be a thyroid of a human body. In this example, the tracer can be a non-radioactive iodine. Since the non-radioactive iodine is introduced into the human body (e.g., injected into the blood of the human body) and then diffuses to the thyroid 104, there can be non-radioactive iodine in the thyroid 104. Alternatively, the non-radioactive iodine can naturally exist in the thyroid 104.

[0055] In an embodiment, the collimator 108 can be positioned between the X-ray detector 102 and the thyroid 104 such that only the X-ray photons that propagate from the thyroid 104 to the X-ray detector 102 along a propagation path that is perpendicular to a reference plane that intersects all the sensing elements 150 of the X-ray detector 102 have a chance to pass through the collimator 108 to reach the X-ray detector 102. Thus, the X-ray photons that propagate from the thyroid 104 toward the X-ray detector 102 along a propagation path that is not perpendicular to the reference plane are blocked and thus prevented by the collimator 108 from reaching the X-ray detector 102.

[0056] In an embodiment, for each point of the thyroid 104, a straight line that passes through the point and is perpendicular to the reference plane intersects the X-ray detector 102. In other words, the projected area of the thyroid 104 onto the reference plane is in the X-ray detector 102. This means that, as Figure 8A shown, the entire thyroid 104 is in a direct view of the X-ray detector 102.

[0057] In an embodiment, the thyroid 104 can be considered to include M imaging slices (including an imaging slice 104a for illustration), where M is an integer greater than 1. An imaging slice of the thyroid 104 can be a thin and wide portion of the thyroid 104. The wide surface of the imaging slice can be flat or curved. It can be said that the imaging slice is confined in one direction in space (e.g., confined in the z-direction (z) of the coordinate system 110). Figure 8AThe M imaging slices are parallel to each other. In another embodiment, the M imaging slices are parallel to the reference plane.

[0058] In an embodiment, the second imaging method may begin with a first slice imaging process of the first imaging slice 104a. Specifically, during the first slice imaging process, essentially only the first imaging slice 104a of the thyroid gland 104 can produce the non-radioactive iodine emission characteristic X-ray photons.

[0059] In this document, "substantially only" means "only or almost only". The meaning of "almost only" can be illustrated by the following example: almost only the non-radioactive iodine in the imaging slice 104a includes (a) the non-radioactive iodine in the imaging slice 104a, and (b) a small region of the non-radioactive iodine outside and adjacent to (i.e., in direct physical contact with) the imaging slice 104a. In other words, almost only the imaging slice 104a may include (a) the imaging slice 104a itself, and (b) a small region of the object 104 outside and adjacent to the imaging slice 104a.

[0060] In an embodiment, the first slice imaging process can be performed by using the radiation source 106 to emit first slice excitation radiation (e.g., X-rays, gamma rays, or subatomic particles) that is essentially only emitted by the first imaging slice 104a, thereby causing the characteristic X-ray photons to be emitted essentially only by the non-radioactive iodine in the first imaging slice 104a.

[0061] In an embodiment, the collimator 108 may be present and positioned such that emitted characteristic X-ray photons propagating only along a propagation path perpendicular to the reference plane toward the X-ray detector 102 can pass through the collimator 108 and strike the sensing element 150 of the X-ray detector 102. Receiving these incident characteristic X-ray photons emitted substantially only in the first imaging slice 104a by the non-radioactive iodine, the X-ray detector 102 captures a first slice image of the non-radioactive iodine substantially only in the first imaging slice 104a.

[0062] Next, in an embodiment, M-1 slice imaging procedures for the remaining M-1 imaging slices of the thyroid 104 are sequentially performed in a similar manner after the first slice imaging procedure for the first imaging slice 104a is performed. Herein, "sequentially" (or "in order" if any) means one at a time and does not imply any particular order of performance. Here, "sequentially" refers to performing the M slice imaging procedures one step at a time and does not imply performing the M slice imaging procedures in any particular order. Overall, the X-ray detector 102 takes M slice images of the non-radioactive iodine in the M imaging slices of the thyroid 104.

[0063] Next, in an embodiment, the M slice images are processed to determine a three- dimensional distribution of the non-radioactive iodine in the thyroid 104. In an embodiment, this processing can be performed using the processor 130 of the system 200. As a result, a physician can examine the three-dimensional distribution of the non-radioactive iodine in the thyroid 104 to understand the thyroid 104.

[0064] Figure 8B A third imaging method for taking a three-dimensional distribution of non-radioactive iodine in the thyroid 104 of the human body according to an embodiment is schematically shown. In an embodiment, the third imaging method can be similar to the second imaging method described above, except that in the third imaging method, the thyroid 104 can be considered to include N imaging strips (including imaging strip 104b for illustration), where N is an integer greater than 1. An imaging strip of the thyroid 104 can be a long and straight piece of the thyroid 104. It can be said that the imaging strip is more narrow in two directions of space (e.g., more narrow in the y and z directions, and not so narrow in the x direction). In an embodiment, the N imaging strips are parallel to each other. In an embodiment, the N imaging strips can be parallel to the reference plane (which intersects all of the sensing elements 150 of the X-ray detector 102).

[0065] In an embodiment, the third imaging method can start from the first imaging strip imaging procedure of the first imaging strip 104b. Specifically, in the first imaging strip imaging procedure, the non-radioactive iodine emission characteristic X-ray photons can be caused to be emitted substantially only in the first imaging strip 104b of the thyroid 104.

[0066] In an embodiment, the first-imaging-strip imaging procedure can be performed by using the radiation source 106 to send first-imaging-strip excitation radiation (e.g., X-ray or gamma-ray or subatomic particles) that passes substantially only through the first imaging strip 104b, causing characteristic X-ray photons to be emitted by the non-radioactive iodine substantially only in the first imaging strip 104b of the thyroid 104.

[0067] In an embodiment, the collimator 108 can be present and positioned so that only the emitted characteristic X-ray photons that propagate along a propagation path that is perpendicular to the reference plane toward the X-ray detector 102 can pass through the collimator 108 and impinge on the sensing elements 150 of the X-ray detector 102. Receiving these incident characteristic X-ray photons that are emitted by the non-radioactive iodine substantially only in the first imaging strip 104b, the X-ray detector 102 takes a first-slice image of the non-radioactive iodine substantially only in the first imaging strip 104b.

[0068] Next, in an embodiment, after performing the first-imaging-strip imaging procedure for the first imaging strip 104b, N-1 strip imaging procedures for the remaining N-1 imaging strips of the thyroid 104 are sequentially performed in a similar manner. Overall, the X-ray detector 102 takes N strip images of the non-radioactive iodine in the N imaging strips of the thyroid 104.

[0069] Next, in an embodiment, the N strip images are processed to determine a three-dimensional distribution of the non-radioactive iodine in the thyroid 104. In an embodiment, this processing can be performed using the processor 130 of the system 200.

[0070] Figure 8C A flowchart summarizing and generalizing the above-described second and third imaging methods is shown. Specifically, referring to Figure 8A 、 Figure 8B and Figure 8C , in step 810, for each imaging region (i.e., imaging slice or imaging strip) of a total of L (L is an integer greater than 1) imaging regions of the subject 104 at a time, characteristic X-rays can be caused to be emitted by the tracer substantially only in the imaging region, and a region image of the tracer substantially only in the imaging region is taken using the characteristic X-rays. The radiation source 106 can be used to send excitation radiation substantially only to the imaging region, causing the tracer substantially only in that imaging region to emit the characteristic X-rays. The X-ray detector 102 can be used to take the region image.

[0071] In an embodiment, the L excitation radiations sent to the L imaging regions can be fan-shaped radiation beams (the L imaging regions are imaging slices). In an embodiment, the L excitation radiations sent to the L imaging regions can be cone-shaped radiation beams (the L imaging regions are imaging strips). In an embodiment, the L excitation radiations sent to the L imaging regions can be collimated radiation beams (the L imaging regions are imaging strips).

[0072] In step 820, a three-dimensional distribution of the tracer in the subject 104 can be determined based on the L taken region images. In an embodiment, the steps 810 and 820 can be repeated multiple times as time progresses to create more three-dimensional distributions of the tracer in the subject 104. By examining these three-dimensional images, one can learn how the tracer moves in the subject 104 as time progresses.

[0073] In the above-described embodiments regarding the second imaging method and the third imaging method ( Figure 8A , Figure 8B and Figure 8C ), a collimator 108 is used. Alternatively, the collimator 108 can be omitted.

[0074] In the above-described embodiments regarding the second imaging method and the third imaging method ( Figure 8A , Figure 8B and Figure 8C ), a non-radioactive iodine is used as the tracer in the thyroid 104 of the human body. In alternative embodiments, a radioactive iodine or a mixture of a radioactive iodine and a non-radioactive iodine can be used as the tracer in the thyroid 104.

[0075] In the above-described embodiments regarding the second imaging method and the third imaging method ( Figure 8A , Figure 8B and Figure 8C ), the subject 104 is the thyroid of the human body. In general, the subject 104 can be a body region of a living organism. For example, the subject 104 can be a body region of the human body just below the skin. In this example, a tracer containing aluminum instead of iodine within the human body region can be of interest (i.e., a three-dimensional distribution of the aluminum tracer in the human body region can need to be determined).

[0076] In some of the above-described embodiments regarding the second imaging method ( Figure 8A ), the M imaging slices are parallel to each other and parallel to the reference plane. In alternative embodiments, the M imaging slices are parallel to each other but not parallel to the reference plane.

[0077] In the above-described embodiments regarding the third imaging method (Figure 8B In some embodiments described above, the N imaging strips are parallel to each other and parallel to the reference plane. In alternative embodiments, the N imaging strips are parallel to each other but not parallel to the reference plane.

[0078] In the embodiments of the second and third imaging methods outlined above with respect to Figure 8C In the embodiments of the second and third imaging methods outlined above with respect to

[0079] In embodiments, if no iodine is present in the imaging region, (a) iodine can be considered to be present in the imaging region but the amount of iodine is zero, (b) the characteristic X-ray photons emitted by iodine in the imaging region can be considered to be present but their number is zero, and (c) the image of iodine taken in the imaging region should show only no-iodine traces.

[0080] Figure 9 Methods of using any of the first, second, and third imaging methods described above Figure 7 and Figure 8C to help locate / identify one or more sentinel lymph nodes are shown.

[0081] In particular, assume that the human body 103 has a tumor 910 in its breast region 104. Further assume that the breast region 104 includes five lymph nodes (lymph node 920.1, lymph node 920.2, lymph node 920.3, lymph node 920.4, and lymph node 920.5) and a lymphatic vessel 930, and that the direction of lymph fluid flow in the lymphatic vessel 930 is from the lymph node 920.5 to the lymph node 920.1, then to the lymph node 920.2, then to the lymph node 920.3 and the lymph node 920.4. As a result, if cancer cells are to spread from the tumor 910, they are likely to flow with the lymph fluid through the lymphatic vessel 930, first to the lymph node 920.1 (because the lymphatic vessel 930 closest to the tumor 910 flows to the lymph node 920.1 first). Thus, the lymph node 920.1 is considered to be the sentinel lymph node of the tumor 910. Thereafter, the cancer cells are likely to continue to spread with the lymph fluid through the lymphatic vessel 930 and to the lymph node 920.2, then to the lymph node 920.3 and the lymph node 920.4.

[0082] Assume that the tumor 910 is diagnosed to have a high risk of being malignant (cancerous). Treatment of the tumor 910 can then begin with the removal of the tumor 910. In addition, to find out if cancer has spread from the tumor 910, the sentinel lymph node 920.1 can also be removed in the same operation and then sent for cancer testing (this operation is commonly referred to as a sentinel lymph node biopsy). If the test result indicates that the removed sentinel lymph node 920.1 is negative for cancer (i.e., no cancer cells are found in the sentinel lymph node 920.1), then it is considered that cancer has not spread from the tumor 910, and thus no further cancer treatment is needed. But if the test result indicates that the removed sentinel lymph node 920.1 is positive for cancer (i.e., cancer cells are found in the sentinel lymph node 920.1), then it is considered that cancer has spread from the tumor 910, and thus further cancer treatment is needed. As an example of additional cancer treatment, the surrounding lymph nodes 920.2, 920.3, 920.4, and 920.5 can also be removed.

[0083] In the above-described sentinel lymph node biopsy, the sentinel lymph node 920.1 of the tumor 910 needs to be identified so that the sentinel lymph node can be removed and sent for cancer testing. In embodiments, any of the first imaging method, the second imaging method, and a third imaging method (described below) Figure 7 and Figure 8C ) can be used to help locate / identify / recognize the sentinel lymph node 920.1 of the tumor 910.

[0084] First, in an embodiment, the tracer may be introduced into the body of the organism 103 (e.g., a human) before using any of the first, second, and third imaging methods. The tracer may be non-radioactive. In an embodiment, the tracer may be introduced into the human body at an introduction site at (or near) the tumor 910. In an embodiment, the tracer may be introduced into the human body by injection.

[0085] Next, in an embodiment, after the tracer is introduced into the body of the organism 103 (e.g., a human body), any one of the first imaging method, the second imaging method, and the third imaging method can be used to help identify / discover the sentinel lymph nodes of the tumor 910. Specifically, as Figure 7 and Figure 8C As shown, any of the first, second, and third imaging methods can be used with the system 200 to sequentially obtain the three-dimensional distribution (i.e., three-dimensional images) of the tracer in the breast region 104. By examining one or more of these obtained three-dimensional distributions, a physician can identify / distinguish the sentinel lymph nodes of the tumor 910.

[0086] More specifically, suppose the physician examines the first three-dimensional distribution of the tracer in the breast region 104 and finds that the tracer has diffused from the introduction site to some lymphatic vessels 930 near the introduction site, but has not yet diffused to any lymph nodes. Suppose the physician subsequently examines the second three-dimensional distribution of the tracer in the breast region 104 (which chronologically follows the first three-dimensional distribution) and finds that the tracer has not only diffused to some of the lymphatic vessels 930 near the introduction site, but also to the first lymph node 920.1. As a result, the physician can identify this first lymph node as the sentinel lymph node at the introduction site. Because the introduction site is at the tumor 910, the first lymph node is also the sentinel lymph node of the tumor 910. Typically, a sentinel lymph node at a location in an organism (e.g., a human or animal) can be defined as the first lymph node, into which free entities from that location (e.g., free cancer cells, injected chemical atoms, lymph atoms, etc.) will first diffuse along with the lymph flowing through the lymphatic vessels.

[0087] Suppose that the physician thereafter examines a third three-dimensional distribution of the tracer in the breast region 104 (which is in chronological order after the second three-dimensional distribution), and finds that the tracer not only diffused to the lymphatic vessel 930 near the introduction site, and thereafter to the first lymph node, but also to the second lymph node. This confirms the physician's earlier identification that the first lymph node 920.1 is the sentinel lymph node of the tumor 910. As mentioned above, by identifying the sentinel lymph node 920.1 of the tumor 910, the physician can remove the sentinel lymph node 920.1 and then send it for cancer testing.

[0088] In short, referring to Figure 9 , the identification of the sentinel lymph node of the tumor 910 can be summarized and generalized as follows. First, a tracer is introduced into a body region 104 (e.g., a breast region) of a living being 103 (e.g., a human body) at (or near) an introduction site of a malignant region 910 (e.g., a tumor). Next, any one of the first, second, and third imaging methods (as described above) can be used to sequentially determine three-dimensional distributions of the tracer in the body region 104. As a result, these obtained three-dimensional distributions show how the tracer diffuses from the introduction site through the lymphatic vessel 930 to the lymph nodes 920 in the body region 104 over time. Thus, by examining one or more of these three-dimensional distributions of the tracer in the body region 104, a physician is able to identify the introduction site and the sentinel lymph node of the malignant region 910. The physician can then remove the sentinel lymph node and send it for cancer testing.

[0089] In the above-described embodiments regarding sentinel lymph node biopsy Figure 9 , the tumor 910 and the introduction site are in the body region to be imaged (i.e., in the breast region 104). Alternatively, the tumor 910 and the introduction site can be outside the body region to be imaged (i.e., outside the breast region 104).

[0090] In the above-described embodiments regarding sentinel lymph node biopsy Figure 9 , any one of the first, second, and third imaging methods can be used to help ascertain / identify the sentinel lymph node 920.1 of the tumor 910 in the living being 103 (e.g., a human body). In general, any one of the first, second, and third imaging methods can be used to help ascertain / identify the sentinel lymph node of a malignant region (e.g., a melanoma, a tumor, etc.) of a living being (e.g., a human body or an animal).

[0091] In the above-described embodiments regarding the sentinel lymph node biopsy, Figure 9 , multiple three-dimensional distributions of the tracer in the breast region 104 can be determined, and one or more of these three-dimensional distributions can be examined to identify the sentinel lymph node of the tumor 910. Alternatively, a first three-dimensional distribution of the tracer in the breast region 104 can be determined, and it can be examined to identify the sentinel lymph node of the tumor 910. If the sentinel lymph node is not identified in the first three-dimensional distribution, a second three-dimensional distribution of the tracer in the breast region 104 can be determined, and it can be examined to determine the sentinel lymph node of the tumor 910. If the sentinel lymph node is not identified in the second three-dimensional distribution, a third three-dimensional distribution of the tracer in the breast region 104 can be determined, and it can be examined to identify the sentinel lymph node of the tumor 910, and so on until the sentinel lymph node of the tumor 910 is identified.

[0092] In the above-described embodiments regarding Figure 9 , it is decided to remove one lymph node 920.1 and to send it for cancer testing. As a result, the sentinel lymph node 920.1 of the tumor 910 needs to be identified. In general, it can be decided to remove K lymph nodes and to send them for cancer testing (K is a positive integer). As a result, K sentinel lymph nodes of the tumor 910 need to be determined. The case K = 1 is described above.

[0093] In the case K = 2, two lymph nodes of the tumor 910 need to be identified and removed, and then they are sent for cancer testing. In the above description, the physician examined the third three-dimensional distribution of the tracer in the breast region 104, and found that the tracer not only spread to the lymphatic vessel 930 near the introduction site and to the first lymph node, but also spread to the second lymph node. As a result, the physician can identify the first lymph node and the second lymph node as two sentinel lymph nodes of the tumor 910, and can remove these two sentinel lymph nodes and send them for cancer testing. In embodiments, if at least one of the two sentinel lymph nodes is positive for cancer, it can be assumed that cancer has spread from the tumor 910, and therefore further cancer treatment is needed.

[0094] In the above-described embodiments regarding Figure 9 Figure 9 , the entire sentinel lymph node 920.1 is removed for cancer testing. In general, a sample can be taken from the sentinel lymph node 920.1, and then it is sent for cancer testing. The sample can include only a portion of the sentinel lymph node 920.1 or the entire sentinel lymph node 920.1.

[0095] 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 claims herein.

Claims

1. A method of imaging a body region of a living being to identify a sentinel lymph node, wherein, The body region includes a tracer introduced into the body region of the organism from the site of introduction of the organism, the method comprising: This causes the emission of characteristic X-rays from the tracer in the body region; Using multiple X-ray detectors located at different positions relative to the body region, images of the tracer in the body region are captured using the characteristic X-rays; Based on the image, a first three-dimensional distribution of the tracer in the body region is determined; and Examine the first three-dimensional distribution of the tracer in the body region; Repeat the foregoing description of eliciting characteristic X-ray emission of the tracer in the body region, capturing an image of the tracer in the body region, and determining the three-dimensional distribution of the tracer in the body region, thereby generating a second three-dimensional distribution of the tracer in the body region; Examine the second three-dimensional distribution of the tracer in the body region; and In the case where the tracer does not diffuse to any lymph nodes in the first three-dimensional distribution, and the tracer diffuses to the first lymph node in the second three-dimensional distribution, the first lymph node is identified as the sentinel lymph node associated with the introduction site, the sentinel lymph node being outside the introduction site.

2. The method of claim 1, further comprising: Repeat the foregoing description of eliciting characteristic X-ray emission of the tracer in the body region, taking an image of the tracer in the body region, and determining the three-dimensional distribution of the tracer in the body region, thereby generating a third three-dimensional distribution of the tracer in the body region. Examine the third three-dimensional distribution of the tracer in the body region; as well as In the case where the tracer diffuses to the first and second lymph nodes in the third three-dimensional distribution, the first lymph node is confirmed to be the sentinel lymph node associated with the introduction site.

3. The method of claim 1, wherein the introduction site is located within a malignant region of the organism.

4. The method of claim 1, wherein the organism is a human body.

5. The method of claim 1, wherein the emission of characteristic X-rays of the tracer in the body region comprises irradiating the body region with excitation radiation.

6. The method of claim 5, wherein the excitation radiation comprises X-rays or gamma rays.

7. The method of claim 1, wherein the tracer is non-radioactive.

8. A method of imaging a body region of a living being to identify a sentinel lymph node, wherein, The body region comprises introducing a tracer into the body region of the living being from an introduction site of the living being, wherein the body region comprises L imaging regions R i , i = 1,..., L, and wherein L is an integer greater than 1, the method comprising: for i = 1,..., L, causing substantially only the tracer emitting characteristic X-ray photons P in the imaging region R i i ;​ For i = 1,..., L, taking an image of a region of the tracer having the characteristic X-ray photons P i in the imaging region R i only essentially in the imaging region R i ; based on the region image I i , i = 1,..., L, determine a first three-dimensional distribution of the tracer in the body region; and Examine the first three-dimensional distribution of the tracer in the body region; Repeat the above description to make it essentially only in the imaging region R i The tracer emitted characteristic X-ray photons P in the [context missing] i The shooting is basically limited to the imaging area R. i The tracer in the present invention has the characteristic X-ray photons P i Regional image I i And, as described above, determining the three-dimensional distribution of the tracer in the body region, thereby generating a second three-dimensional distribution of the tracer in the body region; and Examine the second three-dimensional distribution of the tracer in the body region; In the case where the tracer does not diffuse to any lymph nodes in the first three-dimensional distribution, and the tracer diffuses to the first lymph node in the second three-dimensional distribution, the first lymph node is identified as the sentinel lymph node associated with the introduction site, the sentinel lymph node being outside the introduction site.

9. The method of claim 8, further comprising: Repeat the above description to make it essentially only in the imaging region R i The tracer emitted characteristic X-ray photons P in the [context missing] i The shooting is basically limited to the imaging area R. i The tracer in the present invention has the characteristic X-ray photons P i Regional image I i And, as well as the determination of the three-dimensional distribution of the tracer in the body region, thereby generating a third three-dimensional distribution of the tracer in the body region; and checking the third three-dimensional distribution of the tracer in the body region; in case the tracer diffuses into a first lymph node and a second lymph node in the third three-dimensional distribution, identifying the first lymph node as the sentinel lymph node associated with the introduction site.

10. The method of claim 8, wherein the introduction site is located within a malignant region of the organism.

11. The method of claim 8, wherein the organism is a human body.

12. The method of claim 8, wherein said causing said tracer to emit said characteristic X-ray photons P substantially only in said imaging region R i includes irradiating the imaging region R i with excitation radiation. i 12. The method of claim 8, wherein said causing said tracer to emit said characteristic X-ray photons P substantially only in said imaging region R i includes irradiating the imaging region R i with excitation radiation. i 13. The method of claim 12, wherein the excitation radiation comprises X-rays or gamma rays.

14. The method of claim 8, wherein the tracer is non-radioactive.

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