How safe are X-rays, MRIs, mammograms and CT scans? What you need to know about radiation and health risks

When is it used: Ultrasound is commonly used in obstetrics and gynaecology to monitor foetal development as well as for assessing various medical conditions, according to Matthew.

“It is ideal for soft tissue evaluation, including monitoring pregnancy, assessing abdominal organs, detecting gallstones, and examining blood flow in blood vessels. It is also used for guided procedures such as biopsies,” she said.

Who isn’t suitable: Ultrasound can’t penetrate bone and won’t be able to show what lies within, according to Singhealth.

It also cannot pass through air such as intestinal gas, so an evaluation of the stomach, small intestine and large intestine may be limited. Deeper body parts such as the pancreas and aorta may also be limited, especially if the patient is obese, because body tissue weakens the sound waves the deeper they pass into the body.

4. MAMMOGRAM

What is it: Put simply, it is a specialised X-ray of the breasts. “It can identify abnormalities in the breast before symptoms appear, significantly improving treatment outcomes,” said Matthew.

The scan itself is actually very fast, typically a few seconds, according to Dr Lee. “However, time is needed to position the breast to obtain the best images and this may take an additional 5 to 10 minutes, depending on how many extra images are needed.”

“Also, as compression on the breast tissue is needed,” he highlighted, “it can be a little bit uncomfortable for the patient.”