Insulated Gate Bipolar Transistors or IGBTs are widely used in medical ultrasonography machines to support precise and high voltage pulse generation required for diagnostic imaging. Ultrasound technology is essential in many medical fields including cardiology, obstetrics, urology, neonatology, and gastroenterology, where it is used for non invasive diagnosis and treatment.
Ultrasound refers to sound waves with frequencies above the range of human hearing. In medical imaging, ultrasound frequencies typically range from 2 to 18 megahertz. The selection of frequency involves a balance between image resolution and penetration depth. Lower frequencies penetrate deeper into the body but produce lower resolution images, while higher frequencies provide clearer images with reduced depth.
A handheld probe is used during sonography and is placed over the patient’s body to capture real time images. The probe contains a piezoelectric transducer with a phased array system that allows control of the direction and depth of the sound waves. These waves reflect off internal organs at varying intensities depending on tissue composition. The time taken for echoes to return is used to calculate distance and generate detailed diagnostic images.
To produce ultrasound waves, a high voltage pulse is applied to the piezoelectric material inside the transducer. This pulse often exceeds 1000 volts with current levels between 20 and 50 amperes. However, because the pulse duration is extremely short, typically around 0.5 microseconds and at a repetition rate of about 200 hertz, efficient power control is required.
IGBTs are used in this process to manage energy delivery effectively. The system works by slowly charging a capacitor through a diode while the IGBT is off. The IGBT then turns on briefly to discharge the capacitor through the transducer, producing the required high energy pulse. This method ensures precise control, high efficiency, and reliable operation in medical ultrasound systems.
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