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| - Diagnostic Ultrasound By: Nate Curtis, Bio-Medical Electronics Student, Western Technical College, La Crosse, WI, 10-16-08 Diagnostic ultrasounds are invaluable pieces of medical equipment used by medical professionals on a daily basis. Most people think of diagnostic ultrasound as only being used to see a developing baby, so I will give many other uses of diagnostic ultrasound. In this article I will discuss what diagnostic ultrasound is, what basic parts are in a diagnostic ultrasound machine, and finally I will discuss different types of diagnostic ultrasound. Diagnostic ultrasounds or ultrasonography is a medical imaging technique that uses high frequency sound waves and their echoes. The technique is very similar to the echolocation used by bats, whales and dolphins, as well as SONAR
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| - Diagnostic Ultrasound By: Nate Curtis, Bio-Medical Electronics Student, Western Technical College, La Crosse, WI, 10-16-08 Diagnostic ultrasounds are invaluable pieces of medical equipment used by medical professionals on a daily basis. Most people think of diagnostic ultrasound as only being used to see a developing baby, so I will give many other uses of diagnostic ultrasound. In this article I will discuss what diagnostic ultrasound is, what basic parts are in a diagnostic ultrasound machine, and finally I will discuss different types of diagnostic ultrasound. Diagnostic ultrasounds or ultrasonography is a medical imaging technique that uses high frequency sound waves and their echoes. The technique is very similar to the echolocation used by bats, whales and dolphins, as well as SONAR used by submarines. In diagnostic ultrasounds six actions need to happen. First, the ultrasound machine transmits high-frequency (1 to 20 megahertz) sound pulses into your body using a probe. Second, the sound waves travel into your body and hit a boundary between tissues (e.g. between fluid and soft tissue, soft tissue and bone). Next, some of the sound waves get reflected back to the probe, while some travel on further until they reach another boundary and get reflected. Then, the reflected waves are picked up by the probe and relayed to the ultrasound machine. Next, the ultrasound machine calculates the distance from the probe to the tissue or organ (boundaries) using the speed of sound in tissue (5,005 ft/s or 1,540 m/s) and the time of the each echo’s return, 13 microseconds per centimeter, round trip. Finally, the ultrasound machine displays the distances and intensities of the echoes on the screen, forming a two dimensional or three dimensional image. A typical diagnostic ultrasound setup has seven basic components. The first component is a ultrasound transducer probe. The transducer probe is the main part of the ultrasound machine. The transducer probe makes the sound waves and receives the echoes. The transducer probe generates and receives sound waves using a principle called the piezoelectric (pressure electricity) effect, which was discovered by Pierre and Jacques Curie in 1880. In the probe, there are multiple quartz crystals called piezoelectric crystals. When an electric current is applied to these crystals, they change shape rapidly. The rapid shape changes, or vibrations, of the crystals produce sound waves that travel outward. Conversely, when sound or pressure waves hit the crystals, they emit electrical currents. Therefore, the same crystals can be used to send and receive sound waves. The probe also has a sound absorbing substance to eliminate back reflections from the probe itself, and an acoustic lens to help focus the emitted sound waves. The second component in a basic diagnostic ultrasound setup is a central processing unit (CPU). The CPU is the brain of the ultrasound machine. The CPU is basically a computer that contains the microprocessor, memory, amplifiers and power supplies for the microprocessor and transducer probe. The CPU sends electrical currents to the transducer probe to emit sound waves, and also receives the electrical pulses from the probes that were created from the returning echoes. The CPU does all of the calculations involved in processing the data. Once the raw data are processed, the CPU forms the image on the monitor. The CPU can also store the processed data and/or image on disk. The third component is transducer pulse controls. The transducer pulse controls allow the operator to set and change the frequency and duration of the ultrasound pulses, as well as the scan mode of the machine. The commands from the operator are translated into changing electric currents that are applied to the piezoelectric crystals in the transducer probe. The fourth component of a diagnostic ultrasound setup is the display. The display is a computer monitor which shows the processed data from the CPU. Displays can be black-and-white or color, depending upon the model of the ultrasound machine. The fifth component is a keyboard/cursor. Diagnostic ultrasound machines have a keyboard and a cursor, such as a trackball, built in. These devices allow the operator to add notes to and take measurements from the data. The sixth component of a diagnostic ultrasound setup is disk storage. The processed data and/ or images can be stored on disk. The disks can be hard disks, floppy disks, compact discs or digital video discs. Typically, a patients ultrasound scans are stored on a disk and archived with the patients medical records. The seventh, and final, component is a printer. Many diagnostic ultrasound machines have thermal printers that can be used to capture a hard copy of the image from the display.
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