Understanding the Science Behind Ultrasound Tests:

The term ‘Ultrasound’ literally means sounds belonging to a ‘frequency’ that humans are not able to ‘detect’ or hear.

For most diagnostic applications, this frequency range lies between 2 and 18 megahertz (MHz). Higher frequencies can generate better Ultrasound image quality but are susceptible to getting absorbed (and therefore, ‘diminished in power’) by the skin and other soft tissues.

Lower frequencies can penetrate deeper past the layers of skin & tissues but produce imagesmof a relatively lower resolution and quality. During the process, the Radiologist will hold a wand-like device called the Transducer in his or her hand. The transducer is placed on the patient’s body externally.

In some cases, insertion may be done via the rectum (for males) and vagina (for females) and the Transducer in such situations is ‘placed internally’. Be it external or internal, sound waves are emitted by the machine which travels through the skin and tissue till it reaches a surface that is too dense for it to penetrate further.

The sound waves are then reflected back (similar to the act of light reflecting off a mirror or, say, an echo of our own voice) – resulting in an image. This image or picture is also sometimes referred to as a Sonogram. Different shades of grey indicate different densities of the reflecting surface inside the body, which can be an organ or an internal structure.

Despite being different technically, the terms Ultrasound and sonogram are sometimes used interchangeably.