Sometime in the past few million years, collapse at the top of the cave and surface erosion created the natural entrance of Carlsbad Cavern. This opened previously hidden underground cave passageways to the world above for the first time.
The Society of Diagnostic Medical Sonography (SDMS) defines sonography as diagnostic medical procedure that uses high frequency sound waves (ultrasound) to produce dynamic visual images of organs, tissues, or blood flow inside the body. This type of procedure is often referred to as a sonogram or ultrasound scan.
Diagnostic medical sonography is one of the fastest growing career fields in the health-care industry, with projected growth in new jobs of 44 percent between 2010 and 2020, according to the Bureau of Labor Statistics.