OPG The orthopantomogram (also known as an orthopantomograph, panotomogram or an OPG) is a panoramic single image radiograph of the mandible, maxilla and teeth. It is often OPG encountered in dental practice and occasionally in the emergency department; providing a convenient, inexpensive and rapid way to evaluate the gross anatomy of the jaws and related pathology. Patient position During an OPG the patient remains in a stationary position (seated or standing) while both the x-ray source and film rotate in combination around the patient. The x-ray source rotates from one side of the jaw, around the front of the patient, and then to the other side of the jaw. The film rotates opposite to the x-ray source behind the patient. It takes a few seconds during which the patient must remain completely still. Technical factors panoramic projection paused respiration (departmentally dependent) centering point Frankfort's horizontal line is perpendicular to ...

Linear accelerator , also called  Linac , type of  particle accelerator  ( q.v. ) that imparts a series of relatively small increases in energy to subatomic particles as they pass through a sequence of alternating electric fields set up in a linear structure. The small accelerations add together to give the particles a greater energy than could be achieved by the voltage used in one section alone. linear accelerator Linear accelerator at Stanford (University) Linear Accelerator Center, Menlo Park, Calif. Greg James In 1924  Gustaf Ising, a Swedish physicist, proposed accelerating particles using alternating electric fields, with “drift tubes” positioned at appropriate intervals to shield the particles during the half-cycle when the field is in the wrong direction for acceleration. Four years later, the Norwegian engineer  Rolf Wideröe  built the first  machine  of this kind, successfully accelerating potassium ions to an energy of 50,000 ...

What is an ultrasound? An ultrasound scan is a medical test that uses high-frequency sound waves to capture live images from the inside of your body. It’s also known as sonography. The technology is similar to that used by sonar and radar, which help the military detect planes and ships. An ultrasound allows your doctor to see problems with organs, vessels, and tissues without needing to make an incision. Unlike other imaging techniques, ultrasound uses no radiation. For this reason, it’s the preferred method for viewing a developing fetus during pregnancy. Why an ultrasound is performed Most people associate ultrasound scans with pregnancy. These scans can provide an expectant mother with the first view of her unborn child. However, the test has many other uses. Your doctor may order an ultrasound if you’re having pain, swelling, or other symptoms that require an internal view of your organs. An ultrasound can provide a view of the: bladder brain (in infants) eyes...

  A computed tomography (CT or CAT) scan allows doctors to see inside your body. It uses a combination of X-rays and a computer to create pictures of your organs, bones, and other tissues. It shows more detail than a regular X-ray. You can get a  CT scan  on any part of your body. The procedure doesn't take very long, and it's painless. How Do CT Scans Work? They use a narrow X-ray beam that circles around one part of your body. This provides a series of images from many different angles. A computer uses this information to create a cross-sectional picture. Like one piece in a loaf of bread, this two-dimensional (2D) scan shows a “slice” of the inside of your body. This process is repeated to produce a number of slices. The computer stacks these scans one on top of the other to create a detailed image of your organs, bones, or  blood  vessels. For example, a surgeon may use this type of scan to look at all sides of a tumor to prepare for an o...

A magnetic resonance imaging (MRI) scan is a common procedure around the world. MRI uses a strong magnetic field and radio waves to create detailed images of the organs and tissues within the body. Since its invention, doctors and researchers continue to refine MRI techniques to assist in medical procedures and research. The development of MRI revolutionized medicine. This article looks specifically at MRI scans, how they work, and how doctors use them. Fast facts on MRI scanning MRI scanning is a non-invasive and painless procedure. Raymond Damadian created the first MRI full-body scanner, which he nicknamed the Indomitable. The cost of a basic MRI scanner starts at $150,000 but can exceed several million dollars. Japan has the most MRI scanners per capita, with  48 machines for every 100,000 citizens . What is an MRI scan? Share on Pinterest MRI scans can produce a detailed image. An MRI scan uses a large magnet, radio waves, and a computer to create a d...