Radiology FAQs

What is the difference between a radiologist and a radiographer?
How safe are X-rays?
What is ultrasound?
What is a CAT or CT scan?
What is magnetic resonance imaging (MRI)?
What is nuclear medicine or isotope scanning?
What is fluoroscopy?
What is interventional radiology?
What is a PET scan (positron emission tomography)?
What is a mammography?



What is the difference between a radiologist and a radiographer? 
A radiologist is a doctor who is specially trained to interpret diagnostic images such as X-rays, MRI and CT scans. If you have an interventional procedure (such as an angiogram or biopsy) a radiologist will perform the procedure. Sometimes ultrasound scans may be performed by a radiologist. Radiologists provide a written report of the results of your examination which he or she will send to your doctor.

A radiographer is a person who has been trained to take your X-ray or perform your MRI or CT scan. If a radiographer has been trained to perform an ultrasound, he/she may be called a sonographer. If you have an interventional procedure (such as an angiogram or biopsy) a radiographer will be part of the team looking after you. Some radiographers are also involved in giving radiotherapy treatment to cancer patients.

If you are interested in becoming a radiographer, please contact the Society and College of Radiographers

How safe are X-rays? The risks associated with medical X-rays are frequently exaggerated. It is estimated that the chances of contracting cancer as a result of an X-ray of the chest, for example, are similar to the risks of contracting cancer by inhaling the smoke of one cigarette - about one in a million.

If you are worried about any treatment or scans you may be having, speak again to your GP or the hospital staff. They can refer to your medical records and if they know of your concerns they will always make time to explain the examination or treatment in more detail. You can find out more about radiation from medical X-rays on the Public Health England website.

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What is ultrasound?
Ultrasound consists of high frequency sound waves too high for the human ear to detect, rather like the noise used by bats and dolphins to determine where they are. These waves are emitted by an ultrasound probe and travel harmlessly through the body bouncing off various layers of tissue. The probe then hears these echoes which are relayed onto a screen allowing the pictures to be interpreted. Ultrasound is now the method of choice for monitoring the foetus during pregnancy and in diagnosis of numerous conditions involving organs such as the liver, kidney, heart and blood vessels.

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What is a CAT or CT scan?
Computed axial tomography (CT scan) is simply another X-ray technique using a scanner that takes a series of pictures across the body allowing the radiologist to view the images in two dimensional or three dimensional form. Spiral CT is the most modern form of this imaging with the pictures being produced in only a few seconds.

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What is magnetic resonance imaging (MRI)?
This test is similar to a CT scan but uses magnetism and radio waves to build up a series of cross sectional images. MRI pictures as so precise that they often provide as much information as directly looking at the tissues. For this reason MRI has potential to reduce the number of certain diagnostic procedures. MRI uses no X-rays and the magnetic fields are not known to be harmful. However, it takes longer to obtain the pictures than a conventional X-ray machine, and although the price is coming down all the time, the cost of the equipment means that they are used primarily in those centres where they are kept most busy.

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What is nuclear medicine or isotope scanning?
Radioisotopes give out a very small amount of radiation that can be detected by a specially designed sensitive type of camera. When a radioisotope is linked with certain chemicals it can, harmlessly, trace the workings of the human body. These tests allow radiologists to find alterations in the normal functioning of the body organs, for examples the heart of kidneys, or show early involvement of the body with infections or cancer. The dose of radiation given is very small, but following some tests we do advise that contact with children or breastfeeding mothers should be avoided for a short time. This is particularly the case when radioisotopes have been given in higher doses in order to treat some conditions, for example an overactive thyroid gland, or some types of cancer. Suitable advice will always be given by the radiologist before a patient leaves the hospital.

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What is fluoroscopy?
This machine produces a constant stream of X-rays so that it works in real time, enabling the doctor to view a changing image continuously, as in an interventional procedure. A digital unit produces an image where the picture elements (pixels) have a numerical value and this technology normally delivers a lower dose of radiation than the previous analogue system whilst providing high definition, high resolution images.

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What is interventional radiology?
This encompasses any procedure that is invasive, usually involving the insertion of a needle, cannula (tube), catheter, or wire into the patient for diagnosis and /or treatment. Procedures include angioplasty (insertion of a balloon into a vein or artery to widen it and improve circulation), stenting (insertion of a tube to keep an artery or a vein open) and biopsies e.g. lung, breast, renal, liver, bone etc.

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What is a PET scan (positron emission tomography)?
A diagnostic imaging technique in which patients are given a special radioactive substance that emits positrons which in turn give rise to gamma rays which are detected by a gamma camera.

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What is a mammography?
The technique of using X-rays of the breast to detect irregularities or early signs of cancer.

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