Ultrasound Transducer Components PDF

SIGNAL PROCESSOR The signal processor performs filtering, detection, and compression functions.  SIGNAL PROCESSOR FUNCTIONS: Filtering Filtering eliminates frequencies outside the echo bandwidth while retaining those that are most useful in a given type of operation. SIGNAL PROCESSOR FUNCTIONS:...

SIGNAL PROCESSOR The signal processor performs filtering, detection, and compression functions.  SIGNAL PROCESSOR FUNCTIONS: Filtering Filtering eliminates frequencies outside the echo bandwidth while retaining those that are most useful in a given type of operation. SIGNAL PROCESSOR FUNCTIONS: Detection Detection (demodulation) is the conversion of echo voltages to video form. Echo voltages are produced in a complicated cyclic form (A) called radio frequency (RF), which would be difficult to store and display. Thus the RF form is converted to the simpler amplitude form (B), which retains the amplitude of each echo voltage. SIGNAL PROCESSOR FUNCTIONS: Compression Compression decreases the difference between the smallest and largest amplitudes passing through the system. Compression is operator adjustable as a dynamic range control. This control reduces dynamic range by assigning some weak echo amplitude values to zero or by assigning some of the strongest to maximum. Ultrasound transducer A transducer converts one form of energy to another. Ultrasound transducers convert electric energy into ultrasound energy, and vice versa. Piezoelectric (effect) elements convert electric voltages into ultrasound pulses and convert returning echoes back into voltages. The construction of transducer s  The construction of transducer 5 It consists of five main components: - Crystal/Ceramic Element With Piezoelectric Properties 2 Positive and Ground Electrodes On The Faces Of The Element - Matching Layer - Damping (Backing) Block Housing ~ crystal/ceramic elements The core of an ultrasound transducer is a piezoelectric crystal or ceramic element, typically - made of lead zirconate titanate (PZT). - * This element can be a single piece or part of a - - broadband, multi-element design. - & - crystal/ceramic elements The material used in the transducer's active element can be either natural (e.g., quartz, tourmaline, Rochelle salt), or synthetic, such - - - - - as lead zirconate titanate (PZT), which is favored for its availability -- - & and cost-effectiveness. - r The thickness of this piezoelectric element is important as it determines the resonance frequency => Positive and ground electrodes This allows for an electrical connection Positive electrode is in the back of the element Ground electrode is on the front of the element Damping (backing) block Adhered to the back of the crystal (behind the positive electrode) Absorbs ultrasound energy directed backward and attenuates stray ultrasound signals from the housing Damping reduces pulse duration and spatial pulse length and improves resolution. Matching layer The matching layer serves as an intermediary between the transducer element and body tissues, optimizing ultrasound transmission by reducing reflections at the interface. It achieves this by employing materials with acoustic impedances intermediate to those of soft tissue and the transducer material, often in one or more layers. The active element is typically half a wavelength thick, while each matching layer is a quarter wavelength thick Housing & Electrical insulation and protection of the element Includes a plastic case, metal shield and acoustic insulator Transducer arrays Arrays are transducer assemblies with several transducer elements. The elements are rectangular and are arranged in a straight line or curved line Linear is the adjectival form of the word “line.” Convex means “bowed outward.” Linear Convex