We provide a range of scans and services for patients at NUH
An ultrasound scan builds up a picture of part of the inside of the body using sound waves of a frequency above the hearing range of the human ear.
Ultrasound images complement other forms of scans and are widely used for many different parts of the body. They can also be used to study blood flow and to detect any narrowing or blockage of blood vessels, for example, in the neck.
How does an ultrasound scan work?
A small hand-held sensor, which is pressed carefully against the skin surface, generates sound waves and detects any echoes reflected back off the surfaces and tissue boundaries of internal organs.
The sensor can be moved over the skin to view the organ from different angles, and the pictures are displayed on a TV monitor and recorded for studying later.
Interventional radiology (IR) is surgery that is carried out through the smallest possible incision or through a cannula (small tube), using guidance from X-rays, ultrasound, CT and occasionally MRI. It is an alternative to open surgery, and it is sometimes called pin-hole surgery. Sometimes IR is used as well as other surgery.
Interventional radiologists (IRs) pioneered safe and high quality procedures and standards for performing these ‘minimally invasive therapies’ with a focus on patient safety.
IRs are specialist doctors of radiology, who have completed further education and training in diagnostic radiology and interventional radiology including radiation safety, radiation physics, the biological effects of radiation, injury prevention and clinical practice.
IR therapies typically only require a short stay in hospital and a significant number of these procedures are performed as day cases (this means you will not stay in hospital overnight). General anaesthesia is usually not needed. Risk, pain and recovery time are usually reduced compared to conventional surgery.
How does IR work?
Interventional radiologists have expertise in treating disease by guiding small needles, catheters (tubes) and other medical equipment into the body through the smallest possible incisions in the skin, which are usually only 5-10mm
Magnetic Resonance Imaging (MRI scan)
MRI builds up pictures of an internal cross-section of the part of the body that is being examined. MRI is particularly useful when imaging the body's 'soft tissues' such as the brain and the heart.
How does an MRI scan work?
The large MRI machine contains a ‘tunnel’ about four feet long. You will lie on a couch which is attached to the machine and passes through the ‘tunnel.’ The machine uses a magnetic field and radio waves, together with an advanced computer system, to build up a series of images. Each image shows a thin ‘slice’ of the part of the body being examined. The images are very detailed and give a great deal of information. They can show both bones and soft tissues in the body. Using the computer, the ‘slices’ can be viewed in any direction.
Computed Tomography (CT scan)
A computed tomography (CT) scanner is a special X-ray machine which produces an image of a cross-section or ‘slice’ of the body. The scanner consists of a ‘doughnut’ shaped structure, or gantry, about two feet thick, through which you will be passed on a couch.
How does a CT scan work?
A narrow fan-shaped beam of X-rays is produced from inside the gantry, and rotates in a complete circle around you. The X-rays pass through your body and are detected by electronic sensors on the other side of the gantry. The information passes to a computer which then produces a picture of the internal structure of the body. The pictures are displayed on a TV monitor and can be examined by the radiologist.
It takes about a second to produce each ‘slice’, which can vary in thickness from one millimetre to one centimetre. Depending on how much of the body is being scanned, it will be necessary to produce images of up to 30 or 40 ‘slices’, or possibly higher with some scanners. Most modern CT scanners can do this in less than a minute, so the actual scanning time is fairly short.
Plain film X-ray machine
This is the most common type of imaging used by diagnostic radiographers to visualise bone structures. When used in “real time” like a video they are used to image soft tissue structures such as locating blocked arteries and guiding stent placements.
How do we take an X-ray?
X-rays are produced by an electric current passing through a vacuum, a bit like a fluorescent lamp, when the electricity hits the anode x-rays are produced. The radiographer ensures that the x-rays expose the correct area with the use of a light on the x-ray tube. They use this light to limit the exposure to the x-rays. The x-rays when hitting the detector will produce a digital image. X-rays are like light in that they are electromagnetic waves, but they are more energetic so they can penetrate many materials to varying degrees. Since bone, fat, muscle, tumours and other masses all absorb X-rays at different levels, the image produced on the detector lets you see different structures inside the body. The x-rays are often viewed on a computer screen in the room, the radiographer checks that these are adequate images, they are then passed to a radiologist (x-ray doctor) for reporting.