Ultrasounds are becoming a common diagnostic procedure in the medical field because they can measure and detect abnormalities. Ultrasound instruments which are also known as sonographic instruments operate by using high frequency sound waves. These sound waves operate using a frequency range of 1 to 18 megahertz that can be used for imaging. These high- frequency sound waves are out of range of human hearing. The lower frequency of the sound waves produce less resolution but can produce images deeper into the human body.
Higher frequency sound waves are capable of reflecting or scattering rom smaller structures but are limited to depth of penetration of the sound waves into the body. Ultrasound technology was originally developed in the medical field to view internal organs and make medical diagnosis. It was later used for therapeutic procedures and used to guide physicians in interventional procedures. Ultrasounds are typically performed by a physician or technician with a hand- held probe called a transducer. The transducer is placed directly on the patient and moved around to get images from inside the body.
Depending on the type of ultrasound being performed depends on the frequency used. Deeper structures such as the liver and kidneys need to be imaged at a lower frequency than muscles, tendons, testes, breasts, thyroids, and neonatal brains. While most ultrasound transducers are used on the surface of the body there are special transducers that can be used on the inside of the body. The most common specialty transducers that are used on the inside of the body are endovaginal, endorectal and transesophageal transducer (wiki/ medical_ultrasound).
Ultrasound technology for the medical field was developed in the 1930’s but it was years later before ultrasound devices were commonly used in hospitals. Now ultrasound devices are now common practice in multiple different settings. Ultrasound technology in the medical field is credited due to the past discoveries and continuous improvements. In 1794, Lazzaro Spallanzani, a physiologist discovered how bats, which are blind, traveled with such accuracy by echolocation. Echolocation is the reflection of high frequency sounds.
In 1826, Jean Daniel Colladon, a Swiss physicist, discovered how to calculate the speed of sound underwater with the Under-Water Church Bell. Colladon also discovered that sound waves traveled faster underwater than they did in air. In 1880, Pierre & his brother, Jacques Curie, who were both French physicists, discovered the Piezo-Electric effect which is the connection between electrical voltage and pressure on crystalline material. This is how modern transducers were created. In 1915, Paul Langevin, a physicist invented the first transducer called the hydrophone to detect icebergs and submarines during World War 1.
In 1942, Dr. Karl Dussik, a neurologist and psychiatrist at the University of Vienna was the first physician to use ultrasound for a medical diagnosis of brain tumors. The procedure Dr. Dussik performed was called a yperphonography. In 1948, Dr. George Ludwig M. D. , from the University of Pennsylvania and an internist was the first to use ultrasound technology in the diagnosis of gallstones in animals. In 1958, lan Donald became the pioneer for ultrasound technology after he and Tom Brown built the first successful ultrasound diagnostic device.
Donald was a Scottish professor from the University of Glasgow that became known after a woman with inoperable stomach cancer came to him and he found that it was a cyst through an ultrasound that was then safely removed later. In 1950, Douglass Howry and Joseph Holmes discovered how to improve the 2D B-mode ultrasound at the University of Colorado. Until Howry and Holmes made the improvement of the 2D B-mode ultrasound patients had to be submerged in water in order to produce ultrasound images. 3D ultrasound images began to appear in the 1980’s.
Kazunori Baba from Tokyo, Japan was the first to succeed in obtaining 3D images of fetuses. In the 1990’s ultrasound became more sophisticated with the adoption of 4D real time images. These 4D images are 3D images in motion. Ultrasounds work by using a transducer that produces sound waves that are emitted into the body. In some cases patients re asked to have a full bladder due to the sound waves travel faster through liquid and can improve the quality of the images. The transducer has piezoelectric crystals that when electric current is applied the crystals change shape.
The changing shapes of the crystals produce the sound waves. The type of ultrasound being performed determines the type of transducer and the sound wave frequency that is used. The high frequency sound waves created by the transducer travel through the body and hits the tissue or bone and then reflect back creating an echo. After the echoes make it back to the transducer they hit he crystals. Then the information is sent to a computer that calculates the multiple echoes and then converts them into an image that is then displayed on a screen (nibib).
There are different types of ultrasounds used for different reasons. These different reasons require different types of transducers. There are special transducers that are used for ultrasounds that are done from within the human body. These ultrasounds are transvaginal, transrectual, and transesophageal echocardiograms. Transvaginal ultrasounds are done by using a transducer wand that is placed in a woman’s vagina to view her eproductive organs. These transducers are inserted approximately two or three inches into the vaginal canal to view the uterus, fallopian tubes, ovaries, cervix, and vagina.
There are many reasons transvaginal ultrasounds may be performed such as, unexplained bleeding, pelvic pain, infertility, cysts, and abnormal pelvic or abdominal exam, along with monitoring pregnancy. Transvaginal ultrasounds give a better picture than the traditional ultrasound and is done when a physician feels there is a problem. Physicians can use these ultrasounds to measure organs or unknown masses to help determine a iagnosis. Transrectal ultrasounds are used to diagnose prostate and rectal conditions.
Transrectal ultrasounds are used with a transducer that is inserted into the patient’s rectum. Reasons a physician may do a transrectul ultrasound could be to check for an enlarged prostate, cancer, infertility, or to guide them in biopsy or implant procedures. Transesophageal Echocardiogram uses a transducer probe that is inserted inside the esophagus to get a clearer image of the heart. Transesophageal Echocardiograms are able to give physicians a closer look of the heart without the interference from the ribs or ungs that a traditional echocardiogram can have.
The most common type of ultrasounds are done with a transducer that is pressed against the skin of the patient in the area that is needing to be viewed. Doppler ultrasound are used to estimate blood flow through blood vessels in which the transducer is pressed against the skin in the location which is needing to be viewed. Doppler ultrasounds can diagnose blood clots, heart valve defects, congenital heart disease, blocked artery, bulging arteries, and blood circulation in the legs. Bone sonography is used to determine a diagnosis of early signs of steoporosis.
Musculoskeletal ultrasound is used to diagnose tendon, muscle, or ligament tears, inflammation or fluid of the joints, tumors, cysts, hernias, rheumatoid arthritis and carpal tunnel syndrome. Echocardiogram is used to view the heart to determine any possible conditions. 3D imaging is a three- dimensional image commonly used for imaging unborn babies but are also used in the detection and for the treatment for prostate cancer. 4D imaging is 3D imaging in motion, 4D imaging has grown in popularity with expecting parents because they can see their unborn child in life-like image prior to birth.
