Outlinesrequrements and time Piezoelectric Effeet 15 Effect caused by crystals s changing shape when in an electrical field or when Synthetic ceramic erystals have been developed for medical use that can be molded into various shapes and sizes and focused for ultrasound applications.Each ceramic crystal has a sshortpuscdouves foan resulting in an electrical pulse. Doppler and Color Flow Principles The Doppler Effect waves as they are r the ambulance roached and lower as the vehicle deparis comes higher a c9品wen the mnnro n the medical appication of the Doppler principethe sound ave is bounded of amoving ifpioodcel s along the ine of the ultrasound beam (parallel to fow)the Doppler shift is r in the plane of the beam the fall in frequency is qunywill be increased if flow is toward the sound source (transducer)and decreased The frequency of the returning wave can be converted to spectrum and color. Clinical Correlation The Doppler effec tis helpful in blood vessels and determining optima sites for Typically veins have a low-pitch hum,whereas arteries have an alternating pattern with a high-pitch systolic component and low-pitch diastolic component Instrumentation Ultrasound is used to evaluate sof tis anatomic stru thin all areas of the body energy do5nd3 Outlines, requirements and time allocation Piezoelectric Effect Effect caused by crystals changing shape when in an electrical field or when mechanically stressed , so that a electrical impulse can generate a wave or vice versa Synthetic ceramic crystals have been developed for medical use that can be molded into various shapes and sizes and focused for ultrasound applications. Each ceramic crystal has a resonant frequency that depends on the thickness of the crystal Most diagnostic applications use short ,pulsed ultrasound waves for optimum resolution. As a pulse of ultrasound is emitted , the pulse travels through tissue. When the pulse strikes an interface, part of the energy is reflected. The returning echo is a sound pressure wave that causes a slight mechanical deformation of the ceramic as it impinges on the transducer face, resulting in an electrical pulse. Doppler and Color Flow Principles Doppler physics as it relates to diagnostic ultrasonography concerns the behavior of high-frequency sound waves as they are reflected off moving fluid, usually blood The Doppler Effect The Doppler effect is responsible for the variation in the pitch of the sound wave from an ambulance siren as it moves toward and away from you . The siren pitch becomes higher as the ambulance approached and lower as the vehicle departs The Doppler Principle refers to a change in frequency when the motion of laminar or turbulent flow is detected within a vascular structure. Doppler In the medical application of the Doppler principle the sound wave is bounded off a moving red blood cell. If the cell moves along the line of the ultrasound beam (parallel to flow), the Doppler shift is directly proportional to the velocity of the red cell. If the cell moves away from the transducer in the plane of the beam, the fall in frequency is directly proportional to the velocity and direction of the red blood cell movement. The speed of the moving structure can be calculated from this frequency shift .The returning frequency will be increased if flow is toward the sound source (transducer) and decreased if flow is away from the sound source . The frequency of the returning wave can be converted to spectrum and color. Clinical Correlation The Doppler effect is helpful in localizing blood vessels and determining optimal sites for velocity measurements. Typically veins have a low-pitch hum, whereas arteries have an alternating pattern with a high-pitch systolic component and low-pitch diastolic component. Instrumentation Ultrasound is used to evaluate soft tissue anatomic structures within all areas of the body The patient is examined with a transducer that converts electrical energy into mechanical energy Transducer Frequency Transducers come in many different frequencies –typically 2.5,3.5, 5,7,and 10 MHz. Increasing the frequency improves resolution but decreases penetration. Decreasing the frequency increases penetration but diminishes resolution 15’