What is an MRI?
A diagnostic radiological modality, using nuclear magnetic resonance technology, in which the magnetic nuclei (especially protons) of a patient are aligned in a strong, uniform magnetic field, absorb energy from tuned radiofrequency pulses, and emit radiofrequency signals as their excitation decays. These signals, which vary in intensity according to nuclear abundance and molecular chemical environment, are converted into sets of tomographic (selected planes) images by using field gradients in the magnetic field, which permits 3-dimensional localization of the point sources of the signals.

What is a mammogram?
Imaging examination of the breast by means of x-rays, used for screening and diagnosis of breast disease. Ultrasound and magnetic resonance may also be used to image the breast.

What is radiation oncology?
The medical specialty of radiation therapy; the study of radiation treatment of abnormal tissue growths (malignant or nonmalignant). The doctors who oversee the care of each cancer patient undergoing radiation treatment are called radiation oncologists. They develop and prescribe each cancer patient’s treatment plan. They make sure that every treatment is accurately given. They monitor the patient’s progress and adjust treatment to make sure patients get quality care throughout treatment. Radiation oncologists also help identify and treat any side effects of radiation therapy. They work closely with other physicians, and all members of the radiation oncology team. Radiation oncologists have completed four years of college, four years of medical school, one year of general medical training, then four years of residency (specialty) training in radiation oncology. They have extensive training in the safe use of radiation to treat disease. If they pass a special examination, they are certified by the American Board of Radiology. Patients should ask if their doctor is board certified.

What is ultrasound?
Sound having a frequency greater than 30,000 Hz. Ultrasonography is the location, measurement, or delineation of deep structures by measuring the reflection or transmission of high frequency or ultrasonic waves. Computer calculation of the distance to the sound-reflecting or absorbing surface plus the known orientation of the sound beam gives a two- or three-dimensional image.

What’s the difference between
ultrasonography and Doppler ultrasonography?
Doppler is an application of diagnostic ultrasound used to detect moving blood cells or other moving structures and measure their direction and speed of movement. The Doppler effect is used to evaluate movement by measuring changes in frequency of the echoes reflected from moving structures.
In many instances, Doppler ultrasound has replaced x-ray methods such as angiography, as a method to evaluate blood vessels and blood flow. Doppler ultrasound permits real-time viewing of blood flow that cannot be obtained by other methods. Doppler ultrasound has proved a boon in all areas of ultrasound, aiding in the evaluation of the major arteries and veins of the body, the heart, and in obstetrics for fetal monitoring.

What is fluoroscopy?
Examination of the tissues and deep structures of the body by x-ray, using the fluoroscope.

What is a CT or CAT scan?
Computed tomography (CT) Sometimes referred to as CAT scan (computerized axial tomography). Imaging anatomical information from a cross-sectional plane of the body, each image generated by a computer synthesis of x-ray transmission data obtained in many different directions in a given plane.

Developed in 1967 by British electronics engineer Godfrey Hounsfield, CT has revolutionized diagnostic medicine. Hounsfield linked x-ray sensors to a computer and worked out a mathematical technique called algebraic reconstruction for assembling images from transmission data. In 1973, the Mayo Clinic began operating the first machine in the U.S. Early machines yielded digital images with at least 100 times the clarity of normal x-rays. Subsequently, the speed and accuracy of machines has improved many times over. CT scans reveal both bone and soft tissues, including organs, muscles, and tumors. Image tones can be adjusted to highlight tissues of similar density, and, through graphics software, the data from multiple cross-sections can be assembled into 3-D images. CT aids diagnosis and surgery or other treatment, including radiation therapy, in which effective dosage is highly dependent on the precise density, size, and location of a tumor.

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