Ray transmission intensity-based standard CT value calculation method and detection system

Abstract

The invention discloses a standard CT value calculation method and detection system based on ray transmission intensity, and the method comprises the following steps: S1, transmitting an X ray, and obtaining an incident intensity value Ic and a transmission intensity value Ix of the X ray to a scanned object; s2, an incidence correction value I0 of the incidence intensity value Ic is calculated according to a correction factor Nk, and the correction factor Nk is a correction factor of the intensity meter; s3, calculating a transmission correction value I of the transmission intensity value Ix according to the correction factor Nk; and S4, calculating a standard reference CT value CTs according to the I0 and the I. The detection system comprises a memory, an emission unit, a first calculation unit, a second calculation unit, a third calculation unit, a scanning object and an intensity meter. Compared with the prior art, the calculation method of the reference CT value is established based on the X-ray transmission intensity theory, and a relatively accurate CT value detection result of the CT machine is calculated by adopting a certain mathematical processing method. And secondly, the automation degree is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of CT system standard CT value, and particularly relates to a standard CT value calculation method based on ray transmission intensity and a detection system. BACKGROUND

[0002] The CT value is a key parameter for quantifying the density of tissues in CT images, and its unit is Hounsfield Unit (HU).

[0003] The Hounsfield Unit (HU) is widely used in lesion detection, tissue classification, and radiotherapy planning. The calibration and quality control of a CT (Computed Tomography) photography system is a basic requirement for the use of CT by a medical institution, and the CT device needs to be calibrated and quality controlled regularly to ensure the accuracy of the system CT value.

[0004] Currently, the detection personnel regularly calibrate, verify the accuracy, linearity and consistency of CT value by using standard water phantom or using a body phantom containing multiple materials, and the detection personnel manually selects the region of interest (ROI) segmented by the CT system based on fixed threshold or simple adaptive threshold and calculates the average value. The prior art has the following defects: 1. Since there is a certain deviation in the purity and uniformity of the material of the detection equipment (such as water phantom, body phantom containing multiple materials), the size of the reference value used in the CT value quality control detection process cannot be unified; 2. The CT system is susceptible to noise interference and cannot handle the problem of boundary blur in regions with similar tissue density, and the detection personnel has strong subjectivity and low efficiency when detecting CT, and the detection method requires a large amount of labeled data to train the model, resulting in high detection cost and limited model generalization ability; 3. The selection of ROI relies on human experience and is prone to human error, and the noise and artifacts (such as motion artifacts or metal artifacts) of the equipment cause unstable CT value measurement, and the segmentation accuracy of multiple composite materials is insufficient, which will cause inaccurate CT value measurement. Therefore, when performing quality control detection on the CT value of the CT machine, the existing method is prone to lose control of the accuracy of the CT value. Four, the existing method has certain limitations in judging CT image symptoms. The ability of manual image CT value acquisition is affected by factors such as experience and experience, and these factors inevitably have a lot of subjectivity. The accuracy of the CT value of the CT image system cannot be ignored. The existing technology cannot meet the special requirements of high-precision examination of lesions. Five, at present, the measurement result of the CT value of the CT system is to assign the measured CT system with the standard value of the detection equipment. When detecting the CT value of the CT system using the existing technology, the detection phantom or water phantom is an indispensable detection equipment in the detection process. Due to the influence of processing precision, material purity and stability, the production batches of such detection equipment produced by various manufacturers will inevitably ultimately affect the measurement result of the CT value. Six, since there is no effective traceability method and system for CT value detection results internationally, the current CT value detection result cannot guarantee the unity and effective traceability of the size of the measured CT value, and the detection result of the measured CT value is questionable. SUMMARY

[0005] The present application provides a standard CT value calculation method based on ray transmission intensity and a detection system to solve the problems of non-uniform reference standard CT value, large detection result error, difficulty in determining the accuracy of CT value and low efficiency of manual operation in the prior art.

[0006] In order to solve the above technical problems, the present application provides a standard CT value calculation method based on ray transmission intensity, comprising the following steps:

[0007] S1: emit X-rays to obtain the incident intensity value I of the X-rays on the scanned object c and the transmission intensity value I x ;

[0008] S2: calculating an incident correction value I0 according to the correction factor N k the incident intensity value I c , wherein the correction factor N k is the correction factor of the intensity meter;

[0009] S3: calculating a transmission correction value I according to the correction factor N k the transmission intensity value I x .

[0010] S4: calculating the standard reference CT value CT s by formula (1):

[0011]

[0012] wherein μ w is the attenuation coefficient of X-rays in water, K is a constant, and T is the thickness of the scanned object.

[0013] Preferably, in step S1, the intensity meter is placed above the scanned object, the CT system is started, and the incident intensity value I c of the X-rays on the scanned object is obtained by the intensity meter.

[0014] Preferably, in step S1, the intensity meter is placed below the scanned object, the CT system is started, and the transmission intensity value I x of the X-rays on the scanned object is obtained by the intensity meter.

[0015] Preferably, in step S2, the incident correction value I0 is calculated by formula (2):

[0016] I0 = I c × N k (2).

[0017] Preferably, in step S3, the transmission correction value I is calculated by formula (3):

[0018] I = I x × N k (3).

[0019] Preferably, in formula (2), the incident intensity value I c is the average value of n times of X-ray incident intensity detection results, and the incident intensity value I c is calculated by formula (4):

[0020]

[0021] wherein I i is the i-th incident intensity detection result of X-ray 2;

[0022] In formula (3), the transmission intensity value I x is the average value of n times of X-ray transmission intensity detection results, the transmission intensity value I x is calculated by formula (5):

[0023]

[0024] wherein, U i is the transmission intensity detection result of X-ray 2 at the i-th time.

[0025] Preferably, before step S1, the following step is further included:

[0026] Placing the scanning object in the scanning area of the CT system, starting the scanning of the CT system, and obtaining the positioning image after scanning.

[0027] The application further provides a detection system for calculating the standard CT value based on the X-ray transmission intensity, comprising a memory, a transmitting unit, a first calculating unit, a second calculating unit, a third calculating unit, a scanning object and an intensity meter, wherein the memory is used for storing the correction factor N k and the attenuation coefficient μ w of X-ray in water, the transmitting unit and the intensity meter are used in cooperation to obtain the X-ray incident intensity value I c and the X-ray transmission intensity value I x ; the first calculating unit calculates the incident correction value I0 according to the X-ray incident intensity value I c and the correction factor N k and stores it in the memory, the second calculating unit calculates the transmission correction value I according to the X-ray transmission intensity value I x and the correction factor N k and stores it in the memory; and the third calculating unit calculates the standard reference CT value CT s according to the incident correction value I0 and the transmission correction value I.

[0028] Preferably, the third calculating unit calculates the standard reference CT value CT s according to the following formula:

[0029]

[0030] wherein, μ w is the attenuation coefficient of X-ray in water, K is a constant, and T is the thickness of the scanning object.

[0031] Preferably, the X-ray transmitted by the transmitting unit penetrates the scanning object and the intensity meter above the scanning object, and the intensity meter obtains the incident intensity value I cThe X-ray emitted by the emitting unit penetrates the scanned object and its below, and the intensity meter obtains the transmission intensity value I of the X-ray to the scanned object x .

[0032] Compared with the prior art, the application establishes a calculation method of the reference CT value based on the X-ray transmission intensity theory, obtains the incident intensity value and the transmission intensity value by the intensity meter, and calculates the relatively more accurate CT value detection result of the CT machine by using a certain mathematical processing method, so as to guide the daily quality control detection of the CT machine, evaluate the corresponding performance of the CT machine, and promote the more accurate diagnosis of the lesion in the clinical medical CT image examination. Secondly, the detection system utilizes the existing mature computer technology and data processing technology, has a high degree of automation, eliminates human operation errors to a certain extent, and improves the detection precision and efficiency. Thirdly, it is convenient to trace the source. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0034] Figure 1 It is a structural schematic diagram of X-ray incident intensity measurement of the application;

[0035] Figure 2 It is a structural schematic diagram of X-ray transmission intensity measurement of the application;

[0036] Figure 3 It is a work flow diagram of the application.

[0037] Reference signs:

[0038] 1. Emitting tube, 2. X-ray, 3. Intensity meter, 4. Scanned object. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the application more clear, the technical solutions in the application will be described clearly and completely in combination with the drawings in the application. Obviously, the described embodiments are some embodiments of the application, not all embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the application.

[0040] Referring to the drawings, Figure 3 The embodiment provides a standard CT value calculation method based on ray transmission intensity, which comprises the following steps:

[0041] Step 1: Place the object 4 in the CT system scanning area, start the CT system scanning, and obtain the scanned localization image.

[0042] Step 2: Set the scan plan and intensity meter correction factor N in the CT system. k The emission tube 1 emits X-ray 2, and the incident intensity value I of X-ray 2 on the scanned object 4 is obtained. c and transmission intensity value I x ; Obtain the incident intensity value I of X-ray 2 on the scanned object 4. c and transmission intensity value I x One implementation method: Refer to the appendix Figure 1 Place the intensity meter 3 above the object being scanned 4, start the CT system, and the X-rays 2 emitted by the emission tube 1 penetrate the intensity meter 3 and the object being scanned 4 from top to bottom. The incident intensity value I of the X-rays 2 on the object being scanned 4 is obtained through the intensity meter 3. c ; see attached Figure 2 Place the intensometer 3 below the object being scanned 4, start the CT system, and X-ray 2 penetrates the object being scanned 4 and the intensometer 3 from top to bottom. Obtain the transmission intensity value I of X-ray 2 through the intensometer 3. x Of course, the incident intensity value I of X-ray 2 on the scanned object 4 can also be obtained through a semiconductor dosimeter or a cavity ionization chamber. c and transmission intensity value I x .

[0043] Specifically, the scanning plan includes the exposure sequence (e.g., head exposure sequence), CT system scanning voltage (e.g., 120kV), exposure current-time product (e.g., 200mAs), and the thickness of the scanned object 4 (e.g., T = 10mm).

[0044] Step 3: Based on the correction factor N k Calculate the incident intensity value I c The incident correction value I0 is derived from the metrological standard and obtained through calibration. Specifically, I0 = I c ×N k .

[0045] Step 4: Based on the correction factor N k Calculate the incident intensity value I x The transmission correction value I; specifically, I = I x ×N k .

[0046] Step 5: Calculate the standard reference CT value using formula (1). s :

[0047]

[0048] Wherein: μ w is the attenuation coefficient of X-ray 2 in water, K is a constant (1000), and T is the thickness of the scanned object 4.

[0049] The calculation method provided by the present application is to calculate the standard CT value through the transmission intensity of the X-ray 2 transmitted through the scanned object 4, which can be more accurate as the reference value of the CT value of the CT machine.

[0050] The present application establishes a calculation method of the reference CT value based on the transmission intensity theory of the X-ray 2, and calculates the relatively more accurate CT value detection result of the CT machine by using a certain mathematical processing method, so as to guide the daily quality control detection of the CT machine, evaluate the corresponding performance of the CT machine, and promote the more accurate diagnosis of the lesions in the clinical medical CT image examination.

[0051] In step 2, the intensity meter 3 gives the incident intensity value I c and the transmission intensity value I x in the form of an indication.

[0052] As another embodiment of the present application: in formula (2), the incident intensity value I c is the average value of the n times of X-ray 2 incident intensity detection results, and the incident intensity value I c is calculated by formula (4):

[0053]

[0054] Wherein, I i is the i-th incident intensity detection result of the X-ray 2.

[0055] In formula (3), the transmission intensity value I x is the average value of the n times of X-ray 2 transmission intensity detection results, and the transmission intensity value I x is calculated by formula (5):

[0056]

[0057] Wherein, U i is the i-th transmission intensity detection result of the X-ray 2.

[0058] The above steps can eliminate the random error in the scanning process of the CT system.

[0059] As another embodiment of the present application: the material of the scanned object 4 is one of water, acrylic, polyformaldehyde resin, Teflon, air, polymethylpentene, low-density polyethylene and polyethylene.

[0060] This invention also provides a detection system based on standard CT values ​​calculated from X-ray transmission intensity, comprising a memory, an emission unit, a first calculation unit, a second calculation unit, a third calculation unit, a scanning object 4, and an intensity meter 3. The memory is used to store a correction factor N. k The attenuation coefficient μ of X-rays in water w The emission unit and the intensity meter 3 work together to obtain the incident intensity value I of X-ray 2. c and X-ray 2 transmission intensity value I x The first calculation unit calculates based on the incident intensity value I of X-ray 2. c and correction factor N k The incident correction value I0 is calculated and stored in the memory. The second calculation unit calculates the X-ray 2 transmission intensity value I. x and correction factor N k The transmission correction value I is calculated and stored in the memory; the third calculation unit calculates the standard reference CT value CT based on the transmission correction value I0 and the transmission correction value I. s .

[0061] As another embodiment of the present invention: the third calculation unit calculates the standard reference CT value CT using the following formula. s :

[0062]

[0063] Where: μ w Let be the attenuation coefficient of X-ray 2 in water, K be a constant (1000), and T be the thickness of the scanned object 4.

[0064] In another embodiment of the present invention: when the X-ray 2 emitted by the emitting unit penetrates the scanning object 4 and the intensity meter 3 above it, the intensity meter 3 obtains the incident intensity value I of the X-ray 2 on the scanning object 4. c When the X-ray 2 emitted by the emission unit penetrates the scanning object 4 and the intensity meter 3 below it, the intensity meter 3 obtains the transmission intensity value I of the X-ray 2 through the scanning object 4. x .

[0065] Specifically, the memory is divided into a first memory and a second memory. The first memory is used to store the correction factor N. k The attenuation coefficient μ of X-rays in water w The second storage device is used to store the incident intensity value I of X-ray 2 measured by the intensity meter 3. c and X-ray 2 transmission intensity value I x The second storage unit is also used to store the incident correction value I0 calculated by the first computing unit and the transmission correction value I calculated by the second computing unit.

[0066] The detection system in the application can utilize existing mature computer technology and data processing technology, has high automation degree, eliminates human operation error to a certain extent, and improves detection precision and detection efficiency.

[0067] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for calculating standard CT values ​​based on X-ray transmission intensity, characterized in that, Includes the following steps: S1: Emit X-rays and obtain the incident intensity value I of the X-rays on the scanned object. c and transmission intensity value I x ; S2: Based on the correction factor N k Calculate the incident intensity value I c The incident correction value I0, where the correction factor N k This is the correction factor for the intensity meter; S3: Based on the correction factor N k Calculate the transmission intensity value I x The transmission correction value I; S4: Calculate the standard reference CT value using formula (1). s : Where: μ w Let be the attenuation coefficient of X-rays in water, K be a constant, and T be the thickness of the object being scanned.

2. The method for calculating standard CT values ​​based on X-ray transmission intensity according to claim 1, characterized in that, In step S1, the intensity meter is placed above the object being scanned, the CT system is started, and the incident intensity value I of X-rays on the object being scanned is obtained through the intensity meter. c .

3. The method for calculating standard CT values ​​based on X-ray transmission intensity according to claim 2, characterized in that, In step S1, the intensity meter is placed below the object being scanned, the CT system is started, and the X-ray transmission intensity value I of the object being scanned is obtained through the intensity meter. x .

4. The method for calculating standard CT values ​​based on X-ray transmission intensity according to claim 1, characterized in that, In step S2, the incident correction value I0 is calculated using formula (2): I0=I c ×N k (2)。 5. The method for calculating standard CT values ​​based on X-ray transmission intensity according to claim 4, characterized in that, In step S3, the transmission correction value I is calculated using formula (3): I=I x ×N k (3)。 6. The method for calculating standard CT values ​​based on X-ray transmission intensity according to claim 5, characterized in that, In formula (2), the incident intensity value I c The incident intensity value I is the average of n X-ray incident intensity measurements. c The result is obtained by formula (4): Among them, I i The result of the incident intensity detection of X-ray 2 in the i-th time; In formula (3), the transmission intensity value I x The transmission intensity value I is the average of n X-ray transmission intensity measurements. x The result is obtained by calculation using formula (5): Among them, U i The result of the transmission intensity detection of X-ray 2 in the i-th time.

7. The method for calculating standard CT values ​​based on X-ray transmission intensity according to claim 1, characterized in that, The following steps are included before step S1: Place the object to be scanned in the CT system's scanning area, start the CT system to scan, and obtain the resulting localization image.

8. A detection system based on the calculation of standard CT values ​​of X-ray transmission intensity, characterized in that, It includes a memory, a transmitting unit, a first computing unit, a second computing unit, a third computing unit, a scanning object, and an intensity meter. The memory is used to store the correction factor N. k and the attenuation coefficient μ of X-rays in water w The emitting unit and the intensity meter work together to obtain the X-ray incident intensity value I. c and X-ray transmission intensity value I x ; The first calculation unit calculates based on the X-ray incident intensity value I. c and correction factor N k The incident correction value I0 is calculated and stored in the memory. The second calculation unit calculates the X-ray transmission intensity value I. x and correction factor N k The transmission correction value I is calculated and stored in the memory; the third calculation unit calculates the standard reference CT value CT based on the transmission correction value I0 and the transmission correction value I. s .

9. The detection system based on standard CT value calculation using X-ray transmission intensity according to claim 7, characterized in that, The third calculation unit calculates the standard reference CT value CT using the following formula. s : Where: μ w Let be the attenuation coefficient of X-rays in water, K be a constant, and T be the thickness of the object being scanned.

10. The detection system based on standard CT value calculation using X-ray transmission intensity according to claim 7, characterized in that, When the X-rays emitted by the emission unit penetrate the scanning object and the intensity meter above it, the intensity meter obtains the incident intensity value I of the X-rays on the scanning object. c When the X-rays emitted by the emitting unit penetrate the scanning object and the intensity meter below it, the intensity meter obtains the X-ray transmission intensity value I of the scanning object. x .

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