HIFU hotspot positioning method based on differential CBE
Through a differential CBE imaging system, using sliding window technology and polynomial approximation, the artifacts below the HIFU focus are eliminated, and the artifact problems caused by the thermoacoustic lens effect in ultrasound imaging are solved, and the visual accuracy of the HIFU focus is improved.
Patent Information
- Application Number
- CN202310653550.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-05
- Publication Date
- 2024-12-10
AI Technical Summary
In HIFU focus positioning, ultrasound imaging is affected by the thermal acoustic lens effect, resulting in artifacts below the focus, interfering with the judgment of the HIFU focus position, and it is difficult for the prior artifacts to be effectively eliminated.
Using a differential CBE imaging system, by turning off the time gain compensation function of the ultrasonic system, using sliding window technology and differential CBE calculations, combined with polynomial approximation, eliminate artifacts and improve visualization of HIFU focus.
Effectively suppress artifacts in traditional CBE images, improve the visual accuracy of HIFU focus, and realize clear image monitoring of HIFU focus.
Smart Images
Figure CN119097336A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of medical image segmentation combining computer vision with medical imaging, and relates to a system for eliminating thermoacoustic lens artifacts and realizing HIFU focus positioning. Background Art
[0002] High-intensity focused ultrasound (HIFU) thermal therapy has attracted widespread attention as a promising non-invasive tumor thermal ablation technology. An ideal HIFU procedure should destroy pathological tissue without damaging surrounding normal tissue. However, due to tissue heterogeneity, the HIFU focus on the tissue surface may deviate from the focus inside the tissue. In addition, thermal damage will occur when the tissue temperature is maintained between 50 and 100°C for several seconds (<5s). Therefore, positioning and aiming the HIFU focus during the low temperature stage (<50°C) is a key step in the treatment process.
[0003] At present, there are two main methods for HIFU focal localization in clinical practice, namely magnetic resonance imaging (MRI) and ultrasound (US) imaging. MRI has a temperature accuracy of 1°C and a spatial resolution of 2mm, and is considered to be the most reliable and accurate method for HIFU focal localization and temperature rise quantification. However, MRI equipment is expensive, and the operating environment must meet the requirements of non-ferromagnetic materials and components. In contrast, ultrasound imaging has the advantages of low cost, high compatibility, and real-time imaging, making it a convenient and powerful medical imaging tool. In particular, the backscattered energy conversion (CBE) parameter is linearly related to temperature in the range of 37°C to 50°C, so CBE images have the ability to visualize tissue temperature information. However, due to the influence of the thermoacoustic lens effect, CBE images below the focus may have artifacts, which seriously interfere with the judgment of the HIFU focal position. Therefore, it is urgent to optimize the CBE algorithm to eliminate the artifacts below the focus and achieve clear image monitoring of the HIFU focus before surgery. Summary of the invention
[0004] In order to overcome the defects in the above-mentioned prior art, the present invention provides a HIFU focus positioning system based on differential CBE imaging. This method is further improved on the basis of traditional CBE imaging, and uses radio frequency (RF) signals that have not been corrected by time gain compensation (TGC) for imaging, which can eliminate artifacts below the focus and realize the presentation of the HIFU focus. The technical solution of the present invention is as follows:
[0005] A HIFU focus positioning system based on differential CBE imaging includes a memory, a processor, and a computer program running on the processor. When the processor executes the program, it is used to implement the following method steps:
[0006] The first step is to conduct a graphite phantom experiment and use the Terason 3000 ultrasound imaging system to obtain ultrasound backscatter signals. The TGC function of the ultrasound system needs to be turned off.
[0007] The second step is to use sliding window technology and differential CBE calculation to obtain CBE image:
[0008] (1) The 128 acquired RF data are organized into a two-dimensional array, and then the RF data are demodulated by Hilbert transform to obtain the corresponding envelope image;
[0009] (2) Using a sliding window technique with a 50% window overlap, the image is segmented into multiple small windows with a length of three times the wavelength to obtain local envelope data;
[0010] (3) Using the differential CBE calculation formula Calculate the differential CBE value corresponding to each window;
[0011] (4) The differential CBE values of each small window are reassembled into a differential CBE image, and a differential CBE image of the same size as the original image is obtained through data interpolation;
[0012] In the third step, a polynomial approximation is performed on the differential CBE image to better present the HIFU focus;
[0013] The fourth step is to superimpose the differential CBE image on the B-mode image.
[0014] The characteristics and beneficial effects of the present invention are:
[0015] An imaging system based on differential backscatter energy (DCBE) was proposed and a HIFU burning phantom experiment was conducted. The results showed that ultrasound DCBE imaging inherited the ability of traditional CBE imaging to characterize temperature changes; in addition, ultrasound DCBE imaging can suppress the artifacts below the HIFU focus in traditional CBE imaging and improve the visualization of the HIFU focus. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 Graphite cube experimental framework diagram
[0017] Figure 2 Differential CBE algorithm flow chart
[0018] Figure 3 B-mode image, CBE image, DCBE image
[0019] Figure 4 Differential CBE image overlaid on the B-mode image DETAILED DESCRIPTION
[0020] In order to make the technical solution of the present invention clearer, the present invention is further described below with reference to the accompanying drawings. Figure 1 As shown, the specific steps are as follows:
[0021] The first step is to conduct a graphite phantom experiment and use the Terason 3000 ultrasound imaging system to obtain the ultrasonic backscatter signal. The TGC function of the ultrasound system needs to be turned off.
[0022] Figure 1 The experimental setup is described. Graphite phantom experiments were performed to validate the proposed method. Five phantoms were prepared by dissolving 2 g of agar powder in 200 mL of water and adding 10 g of graphite powder (acoustic scatterer) with a diameter of 20 mm to the agar solution. Each phantom was placed in a box, which was fixed in a water tank and aligned with the focus of HIFU. The temperature in the water tank was controlled at approximately 33 °C by a temperature controller (I-629, ISTA Tech.,). A small hole was drilled in the box to direct the thermocouple sensor (TM-947SD, Lutron Corporation) to the focus of the HIFU system. The HIFU system used in the experiment consisted of a function generator (AFG 3022B, Tektronix Inc., Beaverton, OR, USA), a variable-gain power amplifier (150A100B, Amplifier Research, Souderton, PA, USA), a power meter (Model 4421, Bird Inc., Solon, OH, USA), and a HIFU probe (Sonic Concepts Inc., Bothell, WA, USA). The center frequency of the HIFU probe was 2.12 MHz (bandwidth 1.96–2.28 MHz) and the focal length was 5.5 cm. The output frequency of the function generator was set to 2.12 MHz, and the driving input voltage was a 210 mV (peak-to-peak) continuous sine wave, corresponding to a power of 15 W. A clinical ultrasound system (Model T3000, Terason Inc) equipped with a 3.5 MHz convex array transducer (Model 5C2, Terason Inc., Northborough, MA, USA) with a pulse length of 2.3 mm was used to collect ultrasound backscattered radio frequency (RF) signals. The imaging convex transducer was fixed above the phantom by a Cartesian manipulator to accurately align the imaging plane with the HIFU focus.
[0023] In the second step, the sliding window technique and differential CBE calculation are used to obtain the CBE image, such as Figure 2 As shown:
[0024] (1) The 128 acquired RF data are organized into a two-dimensional array, and then the RF data is demodulated by Hilbert transform to obtain the corresponding envelope image. The envelope image Rk (R0 is defined as the reference image data) at each time point (k = 0, 1, 2, ..., n) is:
[0025]
[0026] (2) Use sliding window technology to divide the image into several small windows to obtain the local envelope The window size is 3 times the wavelength, and the window overlap is 50%, expressed as:
[0027]
[0028] (3) Then, the differential CBE value of each window is calculated according to formula (3):
[0029]
[0030] Where E[·] represents the average statistical value.
[0031] (4) Recombining the DCBE values of each small window into a DCBE image:
[0032]
[0033] η d (x, y) interpolation is the same as R k (x, y) are matrices of the same size and take their absolute values, denoted as |η d |.
[0034] The third step is to d The matrix is approximated and imaged using a 13th-order polynomial and compared with conventional CBE, such as Figure 3 shown.
[0035] The fourth step is to overlay the DCBE image on the B-mode image, such as Figure 4 The present invention proposes that a differential CBE imaging system can present HIFU focus.
Claims
1. A HIFU focus positioning system based on differential CBE, comprising a memory, a processor and a computer program running on the processor. When the processor executes the program, it is used to implement the following method steps: The first step is to conduct a graphite phantom experiment and use the Terason 3000 ultrasound imaging system to obtain ultrasound backscatter signals. The TGC function of the ultrasound system needs to be turned off. The second step is to use sliding window technology and differential CBE calculation to obtain CBE image: (1) The 128 acquired RF data are organized into a two-dimensional array, and then the RF data are demodulated by Hilbert transform to obtain the corresponding envelope image; (2) Using a sliding window technique with a 50% window overlap, the image is segmented into multiple small windows with a length of three times the wavelength to obtain local envelope data; (3) Using the differential CBE calculation formula Calculate the differential CBE value corresponding to each window; (4) The differential CBE values of each small window are reassembled into a differential CBE image, and a differential CBE image of the same size as the original image is obtained through data interpolation; In the third step, a polynomial approximation is performed on the differential CBE image to better present the HIFU focus; The fourth step is to superimpose the differential CBE image on the B-mode image.