For the purpose of medical diagnostic imaging, the sound waves produced by ultrasound equipment are not harmful when properly applied. Diagnostic Medical Sonographers ensure the ALARA principle (as low as reasonably achievable) is followed to limit exposure to what is required to obtain the image. Ultrasound does not use ionizing radiation such as is required for x-ray.
A DMS is a certified technologist who specializes in ultrasound. All of our sonographers are certified under the American Registry of Diagnostic Medical Sonographers (ARDMS) and/or the Canadian Association of Registered Diagnostic Ultrasound Professionals (CARDUP). DMS are certified to practice within the guidelines as set out by the Canadian Association of Radiologists (CAR), Canadian Society of Diagnostic Medical Sonographers (CSDMS) and the Ontario Society of Diagnostic Medical Sonographers (OSDMS). Their education includes both theory and clinical instruction; continuing education programs keep knowledge abreast of both technology and patient care skills.
Sonographers in Canada are trained in one of the following: a 3-year program that requires completion of an allied health education program such as nursing, radiology or nuclear medicine; a bachelor's degree in medical radiation sciences; or a physician who is foreign trained, with an addtional year of full-time theory and clinical ultrasound training.
There are two barriers in producing good quality ultrasound exam images-gas and bone. Contrary to common beliefs, fat is not the main barrier. Sound waves require an appropriate medium to travel through. Air is not considered a medium and therefore blocks the path of the ultrasound beam resulting in a poor image. Bone is a dense, solid medium, however too dense to penetrate and therefore cannot be used to diagnose bone disorders. Liquid is a good conductor and that is
why gel is applied to the skin externally. In this manner the beam from the probe, transmits without interference of barriers.
In order to produce good quality images, the patient is required to fast for at least 8 hours prior to the exam if an abdominal exam has been ordered. This includes chewing gum. The preparation is designed to reduce the amount of gas content in the abdomen. Drinking a small amount of water with medication will not affect the image quality. See our section on exam prep for more information.
The type of ultrasound determines if water needs to be consumed beforehand. If the exam is for pelvis, 40 ounces (1 L) of water is required to be drank at least one hour prior without voiding. A full bladder serves as a window to see neighbouring organs of interest such as uterus, ovaries or prostate. Once the technologist has identified these areas, you will be instructed to empty your bladder and return to finish the imaging. Please do not empty your bladder before the sonographer has instructed you to do so.
Certain abdominal ultrasound exams require fasting for at least 8 hours prior to your exam. This reduces the amount of gas in the abdomen (which obstructs visualization). Eating triggers gastric motility and causes the gall bladder to contract, preventing visualization of abnormalities, such as gall stones.
The results can be immediately called to your doctor if required. Any urgent findings will be called directly as per our urgent medical findings management protocol. The final report will be faxed to your doctor within 24-48 hours.
Sonographers are not permitted to discuss the results with the patient. The results of the examination will be sent to your doctor who will then discuss the findings with you.
Authorized registered users such as physicians and nurse practitioners in the extended class may order an x-ray or ultrasound exam. A registered nurse may complete the order implementing a medical directive. In this case, the RN completes the requisition form, including his or her signature, OHIP Billing number and the name of the physician responsible for the care of the patient and reference to the specific medical directive.
Yes. If you do, please inform the physician who has ordered the exam, as it may determine the course of your treatment.
At StL, “Verbals” mean your examination has been flagged in our system as urgent. It is our protocol to communicate significant medical findings (positive verbal) to the RN or physician who is managing your care. As soon as the images are interpreted by our radiologist, urgent medical results are entered into our reporting queue and a person from our team calls directly. This significantly improves the timing and quality of patient care. The radiology report is generated and faxed within 24 hours.