Ultrasound energy that produces the sound waves is not harmful when properly applied for the purpose of medical diagnostic imaging. Sonographers ensure that they follow the ALARA principle (as low as reasonably acceptable) and limit exposure to what is required. Ultrasound does not use ionizing radiation such as is required for x-ray.
How do you prepare yourself for an ultrasound exam?
There are two barriers in producing a good quality exam –gas and bone. Contrary to what many think, fat is not the main barrier. Sound waves need a medium to travel. Air is not a medium and therefore blocks the path of the ultrasound beam. Liquid is a good conductor and that is why gel is applied to the Healthy Body to allow for greater contact between the probe and skin. Bone is a sense solid medium, too dense for sound to penetrate. As a result, bone disorders cannot be diagnoses by ultrasound.
In order to produce good quality images, the patient is required to fast for at least 8 hours prior to the exam. This reduces the amount of gas content in the abdomen. This includes chewing gum. Drinking water with medication does not prevent the sonographer from attaining good pictures.