Ultrasound (also called sonography) is based on the use of sound waves at much higher frequencies than the range of human hearing. The sound waves are generated by the ultrasonic scanner through a handheld transducer in contact with the patient’s body through a layer of gel. As the sound waves encounter different tissues, they are reflected and scattered to varying degrees; ultrasound is dissipated entirely by bone and air. The transducer receives these echoes and transmits this back to the scanner unit, which interprets the signals and constructs an image. The most basic form of diagnostic ultrasound produces a two-dimensional cross-section of the body. Newer innovations allow for production of three-dimensional images, even in real-time (especially pertinent to imaging the heart or a fetus).

The typical frequency range for diagnostic ultrasound is 1 to 18 MHz; the upper threshold for human hearing is about 20 kHz. The higher the frequency used, the greater axial and lateral resolution (because of smaller waves), but the lower depth of penetration (the waves are more easily dissipated). The ability to image the desired structure, the quality of image produced and the interpretation of the image is also highly operator-dependent. Besides diagnostic imaging, ultrasound is also used for some therapeutic procedures, to destroy tumors, break up kidney stones, treat cataracts, aid in drug delivery within the body, or for guiding biopsies or other procedures. Therapeutic ultrasound procedures may use frequencies outside of the range for imaging and much higher energy.

Compared to other imaging techniques, ultrasound is relatively cheap and the equipment is much more flexible. Portable ultrasound scanners can be brought directly to a patient’s bedside. Also, ultrasound can be used to image a wide variety of bodily systems, including cardiovascular, gastrointestinal, musculoskeletal, urinary and reproductive.

Unlike a number of other imaging techniques, ultrasound does not use ionizing radiation. Rather, because it relies on sound waves, ultrasound is typically considered a safe technique even for fetuses. However, there have been no substantial studies yet of the long-term effects of ultrasound, particularly on subsequent neural development.

Based on a research study* that included 19 facilities throughout the United States with a total of 47 ultrasound imaging exam rooms,
47 rooms/19 facilities = 2.474 rooms/facility on average

For the patient imaging room:
Average area = 152 square feet
Largest area = 235 square feet
Smallest area = 99 square feet

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*Study of imaging department research areas conducted by principal investigators,

David Allison, AIA, ACHA, Professor/Director of Architecture+Health at Clemson University
D. Kirk Hamilton, FAIA, FACHA, Adjunct Professor at Texas A&M University
Frank Zilm, D.Arch, FAIA, FACHA, of Frank Zilm & Associates

with the aid of graduate student investigators,

Megan Gerend of Clemson University
John Grant of Texas A&M University
Scott Weinhoff of Clemson University

and sponsored by,

Academy of Architecture for Health Foundation
American College of Healthcare Architects
Frank Zilm & Associates
McKahan Planning Group, Inc.

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