Method for evaluating skeletal muscle index of head and neck tumor patients by CBCT

Abstract

The present invention discloses a method for evaluating the skeletal muscle index of patients with head and neck tumors by using CBCT. The method utilizes the image-guided radiotherapy technology CBCT, which is routinely used in clinical practice every week before and during radiotherapy for patients with head and neck malignant tumors, to measure the skeletal muscle index of patients with head and neck tumors receiving radiotherapy. Compared with existing skeletal muscle evaluation tools, the method has the advantages of accuracy and low radiation, and saves the detection cost of patients. The method can dynamically evaluate the changes in skeletal muscle of patients with head and neck tumors during radiotherapy, calculate the percentage of skeletal muscle loss, and provide a basis for timely clinical nutritional intervention. The present invention belongs to the field of biomechanical measurement technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomechanical measurement, and more specifically, relates to a method for evaluating the skeletal muscle index of head and neck cancer patients by CBCT. Background Art

[0002] Head and neck malignancies are the seventh most common tumors globally. However, 40% to 50% of head and neck cancer patients are already locally advanced at the time of diagnosis, losing the opportunity for surgery. For inoperable locally advanced head and neck malignancies, radiotherapy combined with chemotherapy is the current standard treatment.

[0003] Radiation mucositis and radiation esophagitis caused by the damage of radiation to the mucosa lead to reduced food intake and weight loss in patients during radiotherapy, and then malnutrition occurs. 44% to 88% of head and neck cancer patients develop malnutrition or worsening malnutrition during radiotherapy. Malnutrition is associated with a series of clinical adverse events such as increased severe radiotherapy adverse reactions, infections, treatment interruptions, decreased body function, decreased quality of life, and reduced survival rate.

[0004] Therefore, it is extremely important to monitor the nutritional status of head and neck cancer patients during radiotherapy, detect malnutrition early and intervene in a timely manner to improve the malnourished state of patients.

[0005] Skeletal muscle is the largest protein reservoir in the body. Skeletal muscle loss is one of the important diagnostic criteria for malnutrition. Timely assessment of skeletal muscle and early intervention in head and neck cancer patients with skeletal muscle loss are important concepts in modern clinical nutrition. Existing skeletal muscle measurement methods include anthropometry, dual-energy X-ray absorptiometry, bioelectrical impedance analysis, and ultrasound examination. Due to poor accuracy, low accessibility, high cost, etc., it is difficult to carry out in clinical practice. Therefore, there is currently a lack of a method for accurately and dynamically evaluating the changes in skeletal muscle of head and neck cancer patients in clinical practice.

[0006] CT uses the principle that different components of body tissues and organs have significant differences in X-ray attenuation to obtain information on various components of the human body such as skeletal muscle, fat, bone, and viscera. By calculating the third lumbar vertebra index to evaluate the body's skeletal muscle content, it is highly correlated with the skeletal muscle area obtained by autopsy, and is an important method for evaluating skeletal muscle in cancer patients. For head and neck cancer patients, the skeletal muscle area of the third cervical vertebra is highly correlated with the skeletal muscle area of the third lumbar vertebra. The neck CT can be scanned to calculate the skeletal muscle area of the third cervical vertebra to evaluate the skeletal muscle index, reducing the CT scan range. Even so, the radiation dose for each CT scan is 10 mSv. Evaluating skeletal muscle by CT additionally increases the radiation dose received by patients, and is expensive with a low economic benefit ratio.

[0007] Therefore, although CT is an accurate method for measuring skeletal muscle mass, its clinical application is greatly limited and it cannot dynamically monitor the changes in skeletal muscle during radiotherapy for patients. Finding a low-cost alternative to CT for radiotherapy patients that can measure skeletal muscle mass and dynamically monitor its changes without additional radiation dose is an urgent problem to be solved in clinical practice.

[0008] CBCT is an image-guided radiotherapy technology developed in recent years. It uses a two-dimensional flat panel detector to collect cone beam ray projection data of an object for volumetric tomography and three-dimensional reconstruction, and is used to monitor and calibrate the radiotherapy position and tumor location of patients. The projection principle of CBCT for obtaining data is different from that of traditional fan-beam CT. The projection data of conventional diagnostic CT is one-dimensional, and the reconstructed image data is two-dimensional. The reconstructed three-dimensional image is composed of a stack of multiple continuous two-dimensional slices; while CBCT is that the X-ray generator makes a circular digital irradiation around the irradiated object with a lower ray dose, and its projection data is two-dimensional, and a three-dimensional image is directly obtained after reconstruction. Therefore, CBCT using cone beam X-ray scanning can significantly improve the utilization rate of X-rays and accelerate the data acquisition speed. Compared with CT, CBCT has a small radiation dose and is an image-guided radiotherapy technology commonly used in clinical practice. Therefore, using CBCT to evaluate the changes in skeletal muscle of radiotherapy patients can not only accurately measure the skeletal muscle mass, but also the regular CBCT examination during radiotherapy can dynamically monitor the changes in skeletal muscle of patients without additional radiation dose and cost to the patients.

[0009] However, due to the characteristics of the cone beam, the low-density resolution in the CBCT projection reconstructed image is lower than that of traditional CT, and the imaging of soft tissues is not as clear as that of traditional CT. How to establish a method for measuring skeletal muscle by CBCT and determine the relevant parameters is the key technical problem for CBCT to be applied to clinical nutritional status assessment. There has been no research at home and abroad to explore the use of CBCT to evaluate and monitor the nutritional status of radiotherapy patients. There has been no research at home and abroad to explore the use of CBCT to evaluate and monitor the nutritional status of radiotherapy patients. Summary of the Invention

[0010] The main purpose of the present invention is to provide a method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT, so as to monitor the loss of skeletal muscle during radiotherapy of head and neck tumor patients at a lower cost.

[0011] According to the first aspect embodiment of the present invention, a method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT is provided, including the following steps:

[0012] 1), Collect CBCT images of head and neck tumor patients during radiotherapy;

[0013] 2), Select a high-resolution reconstruction method to reconstruct the image, and transfer the CBCT image from the linear accelerator to the treatment planning system;

[0014] 3), Mark the skeletal muscle of the cross-section of the third cervical vertebra, move layer by layer from the caudal side to the cranial side, mark the cross-section of the third cervical vertebra at the layer where the transverse process, vertebral arch and spinous process of the third cervical vertebra first appear simultaneously, select the soft tissue window of -300 to +1800 HU, and manually mark the skeletal muscle of the cross-section of the third cervical vertebra, including the bilateral sternocleidomastoid muscles and paravertebral muscles;

[0015] 4), Automatically calculate the skeletal muscle area of the cross-section of the third cervical vertebra;

[0016] 5), Establish a correlation model between CBCT and CT skeletal muscle area, including constructing a database of paired third cervical vertebra skeletal muscles of CBCT and CT;

[0017] 6), Calculate the skeletal muscle index SMI;

[0018] 7), Dynamically track the changes in the skeletal muscle index of the patient during radiotherapy, and monitor the nutritional status of the patient in combination with the patient's weight and nutritional scale.

[0019] According to the method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT according to the embodiment of the first aspect of the present invention, in the step 1), select the CBCT mode on the operation interface of the linear accelerator imaging system, click mode up, select the 3D / 3Dmatch mode, and obtain the scan.

[0020] According to the method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT according to the embodiment of the first aspect of the present invention, in the step 4), each pixel in the CBCT image corresponds to an actual length, and the skeletal muscle area is equal to the length * width * total number of pixels in the skeletal muscle region of the CBCT image.

[0021] According to the method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT according to the embodiment of the first aspect of the present invention, the step 5) includes the following process:

[0022] Collect paired images of the third cervical vertebra of CT and CBCT at the same time for 100 head and neck tumor patients receiving radiotherapy;

[0023] Let multiple tumor radiotherapy physicians independently delineate the skeletal muscle of the cross-section of the third cervical vertebra in the CBCT and CT images respectively;

[0024] Calculate the skeletal muscle areas of the cross-sections of the third cervical vertebra of CBCT and CT respectively;

[0025] Establish a correlation model for the skeletal muscle areas of the paired CBCT and CT images.

[0026] The method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT according to the embodiments of the first aspect of the present invention. In step 5), the formula for the correlation model to obtain the correlation between the CBCT and the skeletal muscle area of the CT paired image is: SMA CT-C3 = 0.2(-0.46; 0.86) + 0.93(0.92; 0.94)SMA CBCT-C3 , where SMA CT-C3 is the skeletal muscle area of the cross-section of the third cervical vertebra of the CT image, and SMA CBCT-C3 is the skeletal muscle area of the cross-section of the third cervical vertebra of the CBCT image.

[0027] The method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT according to the embodiments of the first aspect of the present invention. In step 6), SMI = SMA CT-L3 / H 2 , where SMA CT-L3 is the skeletal muscle area of the cross-section of the third lumbar vertebra of the CT, and H is the height; the relationship between the skeletal muscle areas of the third lumbar vertebra and the third cervical vertebra of the CT image is SMA CT-L3 = 24.078 + 2.789 * SMA CT-C3 , where SMA CT-C3 is the skeletal muscle area of the cross-section of the third cervical vertebra of the CT; thus, the formula for calculating SMI of the skeletal muscle area of the third cervical vertebra CBCT is: SMI = [24.078 + 2.789 * (0.2 + 0.93 * SMA CBCT-C3 )] / H 2 .

[0028] The method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT according to the embodiments of the first aspect of the present invention. Step 7) includes the following process:

[0029] During the radiotherapy of head and neck tumor patients, CBCT image-guided radiotherapy technology is performed weekly;

[0030] Calculate the SMI of the patient every week, and calculate the proportion of SMI loss according to the SMI before radiotherapy;

[0031] Collect the patient's weight, diet, and nutrition scale every week;

[0032] Monitor the patient's nutritional status by combining the changes in SMI with the weight, diet, and nutrition scale, and provide individualized nutritional guidance and treatment.

[0033] According to the method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT according to the embodiments of the first aspect of the present invention, the types of head and neck malignant tumor diseases include one or more of oral cancer, oropharyngeal cancer, nasopharyngeal cancer, laryngeal cancer, hypopharyngeal cancer, and nasal and paranasal sinus malignant tumors.

[0034] One of the technical solutions in the above technical solutions of the present invention has at least the following advantages or beneficial effects: The method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT uses the image-guided radiotherapy technology CBCT, which is routinely used clinically every week before radiotherapy and during radiotherapy for head and neck malignant tumor patients, to measure the skeletal muscle index of head and neck tumor patients receiving radiotherapy. Compared with existing skeletal muscle assessment tools, it has the advantages of accuracy, low radiation, and saves the detection cost of patients; this method can dynamically evaluate the changes in skeletal muscle during radiotherapy of head and neck tumor patients, calculate the percentage of skeletal muscle loss, and provide a basis for timely clinical nutritional intervention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below in conjunction with the drawings and embodiments;

[0036] Figure 1 is a flowchart of the method for measuring the skeletal muscle index of head and neck tumor patients during radiotherapy using CBCT in the present invention;

[0037] Figure 2 is a schematic diagram of the skeletal muscle annotation of the third cervical vertebra of CBCT in the present invention;

[0038] Figure 3 is a schematic diagram of establishing an association model between CBCT and CT skeletal muscle area in the present invention;

[0039] Figure 4 is a schematic diagram of dynamically tracking the changes in the skeletal muscle index of patients during radiotherapy and monitoring the nutritional status of patients in combination with the body weight and nutritional scale of the patients in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0041] In the description of the present invention, it should be understood that the orientation or positional relationship involved, such as up, down, front, back, left, right, etc., indicates the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0042] In the description of the present invention, the meaning of "several" is one or more, the meaning of "multiple" is more than two, and understandings such as "greater than", "less than", "exceeding", etc. do not include the present number, and understandings such as "above", "below", "within", etc. include the present number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0043] In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features.

[0044] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, it can be a fixed connection or a movable connection, or a detachable connection or a non-detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements, indirect communication or the interaction relationship between two elements.

[0045] The following disclosure provides many different embodiments or examples for implementing different solutions of the present invention.

[0046] Refer to Figures 1 to 4 As shown, a method for evaluating the skeletal muscle index of head and neck tumor patients by CBCT is provided, including the following steps:

[0047] 1), Head and neck tumor patients collect kilovolt-level CBCT images during radiotherapy; the purpose of this step is to obtain the CBCT image data of the patients during radiotherapy; during the collection process, the head and neck tumor patients lie supine on the couch of the linear accelerator, place their hands on both sides of the body, and use a head, neck and shoulder plate and a head, neck and shoulder thermoplastic film to fix the patient's body position; select the CBCT mode on the operation interface of the linear accelerator imaging system, click mode up, select the 3D / 3Dmatch mode, and obtain the scan;

[0048] The scanning part is selected as the head and neck, tube voltage: 100 kV, tube current 20 mA, pulse time 10 ms, pixel pitch 0.65 mm, field of view (Field of View, FOV) 25 cm, full fan scanning method, the resolution of the reconstructed CT image is 384*384, the reconstructed slice thickness is 2.5 mm, and a single scan; the head and neck collimator surrounds the entire treatment part, includes the complete third cervical vertebra, the gantry rotates 360°, and three-dimensional images are obtained;

[0049] 2), Reconstruct the image and transmit it. In this step, select the high-resolution reconstruction method to reconstruct the image, and transmit the CBCT image from the linear accelerator to the treatment planning system;

[0050] 3), Mark the skeletal muscles of the cross-section of the third cervical vertebra. Move layer by layer from the caudal to the cephalic direction. Mark the cross-section of the third cervical vertebra at the layer where the transverse process, vertebral arch, and spinous process of the third cervical vertebra first appear simultaneously. Select the soft tissue window of -300 to +1800 HU and manually mark the skeletal muscles of the cross-section of the third cervical vertebra, including the bilateral sternocleidomastoid muscles and paravertebral muscles; All the markings in this step are independently carried out by 3 radiation oncologists with more than 5 years of experience in delineating target areas and organs at risk;

[0051] 4), Automatically calculate the area of the skeletal muscles of the cross-section of the third cervical vertebra. The software used is the Elipse13.5 treatment planning system, and the area calculation tool is MATLAB2019b. In this step, each pixel in the CBCT image corresponds to the actual length, and the skeletal muscle area is equal to the length * width * total number of pixels in the skeletal muscle area of the CBCT image;

[0052] 5), Establish a correlation model between CBCT and CT skeletal muscle areas, including constructing a database of paired CBCT and CT skeletal muscles of the third cervical vertebra; In this step, collect the CT and CBCT images of 100 head and neck tumor patients receiving radiotherapy at the same time, and collect the paired CT and CBCT images of the third cervical vertebra of 100 head and neck tumor patients receiving radiotherapy at the same time; Multiple tumor radiation oncologists independently delineate the skeletal muscles of the cross-section of the third cervical vertebra in the CBCT and CT images respectively; Calculate the skeletal muscle areas of the cross-sections of the third cervical vertebra in CBCT and CT respectively; Establish a correlation model for the skeletal muscle areas of the paired CBCT and CT images; Before the patient's radiotherapy, after 20 radiotherapy sessions, on the day when the CBCT scan is performed at the end of radiotherapy, a CT scan is performed simultaneously;

[0053] CT scan conditions: The CT aperture is 80 cm. The patient lies supine on the table, with both hands placed on both sides of the body. The scan conditions include a voltage of 120 kV, a current of 90 mA, a pixel pitch of 0.975 mm, a FOV of 50, the scan range from the top of the head to the lower edge of the clavicle, and spiral scanning; The resolution of the reconstructed CT images is 384 * 384, the reconstructed slice thickness is 2.5 mm, and the interval is 2.5 mm; The CT images are transmitted to the treatment planning system, and the CT and CBCT images are registered; Mark the cross-section of the third cervical vertebra and the skeletal muscles in CT, select the soft tissue window of 29 to +150 HU, and manually mark the skeletal muscles of the cross-section of the third cervical vertebra. The skeletal muscles include the bilateral sternocleidomastoid muscles and paravertebral muscles; Calculate the skeletal muscle areas of the cross-sections of the third cervical vertebra in CBCT and CT respectively; Establish a correlation model for the skeletal muscle areas of the paired CBCT and CT images;

[0054] The formula for the correlation relationship between the skeletal muscle areas of the CBCT and CT paired images obtained by the correlation model is: SMA CT-C3 = 0.2(-0.46; 0.86) + 0.93(0.92; 0.94)SMA CBCT-C3 , where SMA CT-C3 is the cross-sectional skeletal muscle area of the third cervical vertebra in the CT image, and SMA CBCT-C3 is the cross-sectional skeletal muscle area of the third cervical vertebra in the CBCT image;

[0055] 6) Calculate the skeletal muscle index SMI. The skeletal muscle index SMI is Skeletal Muscle Index; SMI = SMA CT-L3 / H 2 , where SMA CT-L3 is the cross-sectional skeletal muscle area of the third lumbar vertebra in the CT, and H is the height; the relationship between the skeletal muscle areas of the third lumbar vertebra and the third cervical vertebra in the CT image is SMA CT-L3 = 24.078 + 2.789 * SMA CT-C3 , where SMA CT-C3 is the cross-sectional skeletal muscle area of the third cervical vertebra in the CT; thus, the formula for calculating SMI of the third cervical vertebra CBCT skeletal muscle area is: SMI = [24.078 + 2.789 * (0.2 + 0.93 * SMA CBCT-C3 )] / H 2 ;

[0056] 7) Dynamically track the changes in the skeletal muscle index of the patient during radiotherapy, and combine the patient's weight and nutrition scale to monitor the patient's nutritional status; for head and neck cancer patients during radiotherapy, perform CBCT image-guided radiotherapy technology weekly; calculate the patient's weekly SMI, and calculate the proportion of SMI loss based on the SMI before radiotherapy; collect the patient's weight, diet, and nutrition scale weekly; the change in SMI combined with the weight, diet, and nutrition scale monitors the patient's nutritional status, and provides individualized nutritional guidance and treatment.

[0057] In some embodiments of the present invention, the types of head and neck malignant tumor diseases include one or more of oral cancer, oropharyngeal cancer, nasopharyngeal cancer, laryngeal cancer, hypopharyngeal cancer, and nasal and paranasal sinus malignant tumors.

[0058] This method for evaluating the skeletal muscle index of head and neck cancer patients by CBCT uses the CBCT image-guided radiotherapy technology, which is routinely used clinically before and weekly during radiotherapy for head and neck cancer patients, to measure the skeletal muscle index of head and neck cancer patients receiving radiotherapy. Compared with existing skeletal muscle assessment tools, it has the advantages of accuracy, low radiation, and saves the patient's detection cost; this method can dynamically evaluate the skeletal muscle changes of head and neck cancer patients during radiotherapy, calculate the percentage of skeletal muscle loss, and provide a basis for timely clinical nutritional intervention.

[0059] In some embodiments of the present invention, in step 5) of this embodiment, a method for labeling the skeletal muscle of the third cervical vertebra cross-section is provided, including the following steps:

[0060] First step, move layer by layer from the caudal side to the cranial side, and the layer where the transverse process, vertebral arch, and spinous process of the third cervical vertebra first appear simultaneously is labeled as the cross-section of the third cervical vertebra;

[0061] Second step, select a soft tissue window of -300 to +1800 HU, and manually mark the skeletal muscle of the third cervical vertebra cross-section. As Figure 2 shown, the skeletal muscle includes bilateral sternocleidomastoid muscles and paravertebral muscles;

[0062] All the markings in this step are independently performed by 3 radiation oncology physicians with more than 5 years of experience in delineating target areas and organs at risk.

[0063] In some embodiments of the present invention, in step 5), a method for establishing an association model between CBCT and CT skeletal muscle area is also provided. Refer to Figure 3 , and the model establishment includes the following steps:

[0064] Construct a database of the third cervical vertebra skeletal muscle of CBCT-CT pairs, collect CT and CBCT images of 100 head and neck tumor patients receiving radiotherapy at the same time during radiotherapy, and register the CT and CBCT images;

[0065] Move the images layer by layer from the caudal side to the cranial side, and the layer where the transverse process, vertebral arch, and spinous process of the third cervical vertebra appear simultaneously is labeled as the cross-section of the third cervical vertebra.

[0066] Three experienced oncology radiotherapy physicians (with more than 5 years of work experience, able to independently delineate target areas and organs) independently delineate the skeletal muscle of the third cervical vertebra cross-section of CBCT and CT images. The skeletal muscle includes bilateral bilateral sternocleidomastoid muscles and paravertebral muscles;

[0067] Respectively calculate the skeletal muscle areas of the third cervical vertebra cross-sections of CBCT and CT;

[0068] The software used is the Elipse13.5 treatment planning system, the area calculation tool is MATLAB2019b, and the calculation method is: the actual length corresponding to each pixel in the image, area = length * width * total number of pixels;

[0069] Establish an association model for the skeletal muscle areas of CBCT-CT paired images.

[0070] In this step, a linear regression model is used, and the fitting formula is: SMA CT-C3 = 0.2(-0.46; 0.86)+0.93(0.92; 0.94)SMA CBCT-C3 , SMACT-C3 The cross-sectional skeletal muscle area of the third cervical vertebra in the CT image, SMA CBCT-C3 The cross-sectional skeletal muscle area of the third cervical vertebra in the CBCT image.

[0071] In some embodiments of the present invention, in step 6, a process of dynamically tracking the changes in the skeletal muscle index of a patient during radiotherapy and monitoring the nutritional status of the patient in combination with the patient's weight and nutrition scale is also provided. See Figure 4 , the steps include:

[0072] The first step, during the radiotherapy of head and neck tumor patients, at the time before radiotherapy, the CBCT image-guided radiotherapy technology is performed every week during radiotherapy;

[0073] The second step, mark the cross-section of the third cervical vertebra, and mark the skeletal muscles of the cross-section of the third cervical vertebra, including the bilateral sternocleidomastoid muscles and paravertebral muscles.

[0074] The third step, automatically calculate the skeletal muscle area SMA of the cross-section of the third cervical vertebra in the CBCT CBCT-C3

[0075] The fourth step, calculate the SMI of the patient per week. The calculation formula: SMI = [24.078 + 2.789 * (0.2 + 0.93 * SMA CBCT-C3 )] / H 2 ;

[0076] Continuously and dynamically record the changes in SMI per week, and calculate the proportion of SMI loss.

[0077] Collect the patient's weight, diet and nutrition scale every week, such as dietary survey, nutrition screening scale NRS2002, nutrition assessment scale PG-SGA. The time interval between data collection and CBCT scanning does not exceed ±3 days.

[0078] The changes in SMI are combined with the weight, diet and nutrition scale to monitor the nutritional status of the patient, and individualized nutritional guidance and treatment are given.

[0079] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that: various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. Method for evaluating skeletal muscle index of head and neck tumor patients by CBCT, which is characterized in that, it includes the following steps: 1), During radiotherapy, CBCT images are collected from head and neck tumor patients; 2), Select a high-resolution reconstruction method to reconstruct the images, and transmit the CBCT images from the linear accelerator to the treatment planning system; 3), Mark the skeletal muscle at the cross-section of the third cervical vertebra, move layer by layer from the caudal to the cephalic direction, mark the cross-section of the third cervical vertebra at the layer where the transverse process, vertebral arch and spinous process of the third cervical vertebra first appear simultaneously, take the soft tissue window of -300 to +1800 HU, and manually mark the skeletal muscle at the cross-section of the third cervical vertebra, including bilateral sternocleidomastoid muscles and paravertebral muscles; 4), Automatically calculate the skeletal muscle area at the cross-section of the third cervical vertebra; 5) Establish a CBCT-CT skeletal muscle area correlation model, including constructing a database of the third cervical vertebra skeletal muscles paired with CBCT and CT. The formula for the correlation relationship between the skeletal muscle areas of the CBCT-CT paired images obtained from the correlation model is: SMA CT-C3 = 0.2(-0.46; 0.86) + 0.93(0.92; 0.94)SMA CBCT-C3 , where SMA CT-C3 is the cross-sectional skeletal muscle area of the third cervical vertebra in the CT image, and SMA CBCT-C3 is the cross-sectional skeletal muscle area of the third cervical vertebra in the CBCT image; 6) Calculate the skeletal muscle index SMI, where SMI = SMA CT-L3 / H 2 , where SMA CT-L3 is the cross-sectional skeletal muscle area of the third lumbar vertebra in the CT scan, and H is the height; the relationship between the cross-sectional skeletal muscle areas of the third lumbar vertebra and the third cervical vertebra in the CT image is SMA CT-L3 = 24.078 + 2.789 * SMA CT-C3 , where SMA CT-C3 is the cross-sectional skeletal muscle area of the third cervical vertebra in the CT scan; thus, the formula for calculating SMI of the cross-sectional skeletal muscle area of the third cervical vertebra in the CBCT scan is: SMI = [24.078 + 2.789 * (0.2 + 0.93 * SMA CBCT-C3 )] / H 2 ; 7), Dynamically track the changes in the skeletal muscle index of patients during radiotherapy, and monitor the nutritional status of patients in combination with the patients' body weight and nutrition scale.

2. The method for evaluating skeletal muscle index of head and neck tumor patients by CBCT according to claim 1, which is characterized in that: In step 1), on the operation interface of the linear accelerator imaging system, select the CBCT mode, click mode up, select the 3D / 3Dmatch mode, and obtain the scan.

3. The method for evaluating skeletal muscle index of head and neck tumor patients by CBCT according to claim 1, which is characterized in that: In step 4), each pixel in the CBCT image corresponds to an actual length, and the skeletal muscle area is equal to the length * width * total number of pixels in the skeletal muscle area in the CBCT image.

4. The method for evaluating skeletal muscle index of head and neck tumor patients by CBCT according to claim 1, which is characterized in that, step 5) includes the following process: Collect paired CT and CBCT images of the third cervical vertebra of 100 head and neck tumor patients receiving radiotherapy at the same time; Multiple oncology radiotherapy physicians independently delineate the skeletal muscle at the cross-section of the third cervical vertebra in the CBCT and CT images respectively; Calculate the skeletal muscle areas at the cross-sections of the third cervical vertebra in CBCT and CT respectively; Establish a correlation model for the skeletal muscle areas of CBCT and CT paired images.

5. The method for evaluating skeletal muscle index of head and neck tumor patients by CBCT according to claim 4, which is characterized in that, step 7) includes the following process: During radiotherapy of head and neck tumor patients, CBCT image-guided radiotherapy technology is performed weekly; Calculate the SMI of the patient every week, and calculate the proportion of SMI loss based on the SMI before radiotherapy; Collect the patient's body weight, diet and nutrition scale every week; Monitor the nutritional status of the patient by combining the changes in SMI with the body weight, diet and nutrition scale, and provide individualized nutritional guidance and treatment.

6. The method for evaluating skeletal muscle index of head and neck tumor patients by CBCT according to any one of claims 1 to 5, which is characterized in that: The types of head and neck malignant tumor diseases include one or more of oral cancer, oropharyngeal cancer, nasopharyngeal cancer, laryngeal cancer, hypopharyngeal cancer, and malignant tumors of the nasal cavity and paranasal sinuses.

Images