Debugging of ultrasonic imaging diagnostic instrument
Ultrasonic imaging has been widely used in the diagnosis of surgery, cardiovascular, oncology, gastroenterology, ophthalmology, obstetrics and gynecology and other diseases. In recent years, on the one hand, the development of ultrasonic imaging diagnostic instrument constantly explore the clinical of new applications, on the other hand as the ultrasound imaging in the diagnosis of experience and understanding of the performance of ultrasonic imaging instrument, physicians and function in the quality of ultrasonic imaging diagnostic instrument and often put forward various requirements and Suggestions, so that not only promote the ultrasonography diagnosis level enhances unceasingly, Moreover, the application of ultrasonic imaging has been deepened, and the diagnostic technology of ultrasonic imaging has been developed.
1. Monitor debugging
To obtain a high quality image of diagnostic value, various conditions are required. Among them, the debugging of ultrasonic diagnostic instrument monitor is very important. After the host and monitor are powered on, the initial image is displayed on the screen. Check whether the gray ribbon is complete before debugging, and put the post-processing in a linear state. The contrast and Lright of the monitor can be adjusted as much as desired. Debug the monitor to make it suitable, even if it adequately reflects the various diagnostic information provided by the host, and is acceptable to the diagnocian’s vision. The grayscale is used as the standard during debugging, so that the lowest grayscale is faintly visible in black. The highest gray level is white character brightness but bright, adjust to all levels of gray level rich and can be displayed.
2. Sensitivity debugging
Sensitivity refers to the ability of the ultrasound diagnostic instrument to detect and display interface reflections. It consists of total gain, near field suppression and remote compensation or depth gain compensation (DGC). The total gain is used to adjust the amplification of voltage, current or power of the received signal of the ultrasonic diagnostic instrument. The level of the total gain directly affects the display of the image, and its debugging is very important. In general, normal adult liver is selected as the adjustment model, and the real-time image of right liver containing middle hepatic vein and right hepatic vein is displayed by subcostal oblique incision, and the total gain is adjusted so that the echo intensity of liver parenchyma in the middle of the image (4-7cm area) is as close as possible to the gray scale displayed in the middle of the gray scale. Depth gain compensation (DGC) is also known as time gain compensation (TGC), sensitivity time adjustment (STC). As the distance of incident ultrasonic wave increases and weakens in the propagation process of human body, the near-field signal is generally strong, while the far-field signal is weak. In order to obtain an image of uniform depth, near field suppression and far field compensation must be carried out. Each kind of ultrasonic instrument generally adopts two kinds of compensation forms: zoning control type (slope control type) and subsection control type (distance control type). Its purpose is to make the echo of near field (shallow tissue) and far field (deep tissue) close to the gray level of middle field, that is, to obtain a uniform image from light to deep gray level, so as to facilitate the interpretation and diagnosis of doctors.
3. Adjustment of dynamic range
Dynamic range (expressed in DB) refers to the range of the lowest to highest echo signal that can be amplified by the amplifier of the ultrasonic imaging diagnostic instrument. The echo signal indicated on the image below the minimum is not displayed, and the echo signal above the maximum is no longer enhanced. At present, the dynamic range of the strongest and lowest echo signals in the general ultrasonic imaging diagnostic instrument is 60dB. ACUSONSEQUOIA computerized ultrasound machine up to 110dB. The purpose of adjusting the dynamic range is to fully expand the echo signal with important diagnostic value and to compress or delete the non-important diagnostic signal. The dynamic range should be freely adjustable according to diagnostic requirements.
The appropriate dynamic range selection should not only ensure the display of low and weak echo signal inside the lesion, but also ensure the prominent of the lesion boundary and strong echo. The general dynamic range required for abdominal ultrasound diagnosis is 50~55dB. However, for careful and comprehensive observation and analysis of pathological tissues, a large dynamic range can be selected and image contrast can be reduced to enrich the diagnostic information displayed in the acoustic image.
4. Adjustment of beam focusing function
Scanning human tissues with focused acoustic beam can improve the resolution of ultrasound on the fine structure of focus area (lesion), and reduce the generation of ultrasonic artifacts, thus improving the image quality. At present, ultrasonic focusing mainly adopts the combination of real-time dynamic electron focusing, variable aperture, acoustic lens and concave crystal technology, so that the reflection and reception of ultrasonic can achieve the full range of highly focused in the near, middle and far fields. For the ultrasonic diagnostic instrument with the function of segmentalized focusing selection, the depth of focusing can be adjusted by physicians at any time during operation.
Post time: May-21-2022