Medical imaging

Medical imaging covers a range of procedures used to see inside the body, which can give valuable information about your health. These include:

• X-rays
• computed tomography (CT or 'CAT' scan)
• magnetic resonance imaging (MRI)
• ultrasounds

You will need a referral from your treating doctor before booking an appointment for a medical imaging procedure.

Risks

Cancer risks from medical radiation are very small. To help us ensure these risks remain low please let staff know if you are pregnant or have had any recent X-rays or scans.

Before your medical imaging procedure, you may be asked to sign a consent form stating that you understand and accept the risks involved. If you have any questions about the procedure, please ask your doctor or the medical imaging staff.

Types of medical imaging

X-rays

X-rays are the most common imaging procedure. They are used to look inside the body-usually to see broken bones, the chest or teeth-and use very low amounts of radiation.

You will be asked to stand, sit or lie down in a position that gives the best image.

The procedure takes only a few minutes.

Computed tomography (CT or 'CAT' scan)

Computed tomography (CT) or 'CAT' scans create cross-sectional pictures of the body using X-rays and a computer.

CT is used when your doctor needs more information than what an ordinary X-ray can provide.

The CT machine looks like a large doughnut with a narrow table in the middle that the patient lies on. The table moves through the circular hole in the centre of the scanner.

The radiographer (the person controlling the scanning equipment) will not be in the room during the scan, but they will be able to see and communicate with you through an intercom.

During the scan, you will hear a whirring or humming noise and feel the table move slowly through the scanner. You should remain as still as possible, as the slightest movement can blur the pictures.

The procedure is painless and the machine is open at both ends so patients are unlikely to feel claustrophobic.

For some scans, you will be asked to hold your breath for up to 20 seconds.

The whole procedure takes approximately 10 to 20 minutes, depending on what part of the body is being scanned.

For some scans you will need to drink or be injected with a special fluid to help in the imaging. The medical imaging staff will be able to provide details of this if it is needed.

Magnetic resonance imaging (MRI)

MRI is an advanced imaging method that uses a strong magnetic field, radio waves and a computer to create pictures of the body. It does not use X-rays or medical radiation.

MRI pictures are very detailed—they can show both bones and soft tissue in the body.

Like the CT machine, the MRI looks like a large doughnut with a narrow table in the middle that the patient lies on. The table moves through the circular hole in the centre of the scanner.

The procedure is painless, but some people find that being inside the MRI machine makes them feel uncomfortable due to the confined space of the tunnel. If this occurs, let the staff know.

All metal objects must be removed from your body—for example, jewellery, eyeglasses and mobile phones—before the procedure.

Because of the strong magnetic field there some patients are not able to have an MRI.

These may include people with: heart pacemakers, aneurysm clips in the brain, and foreign bodies such as metal shavings in the eyes. It is vital that you answer the safety questions as correctly as possible before your procedure. You should discuss any internal implants that you may have with MRI staff.

Ultrasound

Ultrasound scans assess internal organs and help to diagnose a variety of conditions.

They are also performed to assess disease in the arteries or veins.

An ultrasound machine is made up of a computer, a display screen and a probe (transducer). The probe is a small handheld device that resembles a microphone.

Ultrasound pictures are produced by passing ultrasonic (high-frequency) soundwaves into the scanned area. It does not use X-rays or medical radiation.

An ultrasound is a painless procedure, but you may feel pressure or minor discomfort from the probe if a tender area is scanned.

The lights in the room will be dimmed so that the pictures on the screen can be seen more clearly.

A gel will be applied to your skin over the area to be scanned. The gel allows the probe to slide easily over the skin and helps produce clearer pictures.

The probe will be moved back and forth slowly over the area of interest until the area is completely examined.

You could be asked to hold your breath, or roll into different positions during the scan.

The ultrasound will take 15–60 minutes, depending on the body part being scanned and the type of investigation needed.

Locations

Your doctor can let you know of suitable services, or you can find a health service.