An X-ray is a high frequency, high energy wave form. It cannot be seen with the naked eye, but can be picked up on photographic film. Although you may think of an X-ray as a picture of bones, a trained observer can also see air spaces, like the lungs (which look black) and fluid (which looks white, but not as white as bones). What to expect? You will have all metal objects removed from your body. You will be asked to remain still in a specific position and hold your breath on command. There are staff present, but they will not necessarily remain in the room, but will speak with you via an intercom system and will be viewing the procedure constantly through a windowed control room. The examination time will vary depending on the type of procedure required, but as a rule it will take around 30 minutes. Read more about x-ray imaging here

With CT you can differentiate many more things than with a normal X-ray. A CT image is created by using an X-ray beam, which is sent through the body from different angles, and by using a complicated mathematical process the computer of the CT is able to produce an image. This allows cross-sectional images of the body without cutting it open. The CT is used to view all body structures but especially soft tissue such as body organs (heart, lungs, liver etc.). What to expect? You will have all metal objects removed from your body. You will lie down on a narrow padded moveable table that will be slid into the scanner, through a circular opening. You will feel nothing while the scan is in progress, but some people can feel slightly claustrophobic or closed in, whilst inside the scanner. You will be asked to remain still and hold your breath on command. There are staff present, but they will not necessarily remain in the room, but will speak with you via an intercom system and will be viewing the procedure constantly through a windowed control room, from where they will run the scanner. Some procedures will require Contrast Medium. Contrast medium is a substance that makes the image of the CT or MRI clearer. Contrast medium can be given by mouth, rectally, or by injection into the bloodstream. The scan time will vary depending on the type of examination required, but as a rule it will take around 30 minutes. Read more about CT scanning here

An MRI machine does not work like an X-ray or CT; it is used for exact images of internal organs and body structures. This method delivers clear images without the exposure of radiation. The procedure uses a combination of magnetic fields and radio waves which results in an image being made using the MRI’s computer. What to expect? You will have all metal objects removed from your body. You will lie down on a narrow padded moveable table that will be slid into the scanner, through a circular opening. You will feel nothing while the scan is in progress, but some people can feel slightly claustrophobic or closed in, whilst inside the scanner. You will be asked to remain still and hold your breath on command. There are staff present, but they will not necessarily remain in the room, but will speak with you via an intercom system and will be viewing the procedure constantly through a windowed control room, from where they will run the scanner. Some procedures will require Contrast Medium. Contrast medium is a substance that makes the image of the CT or MRI clearer. Contrast can be given by mouth, rectally, or by injection into the bloodstream. The scan time will vary depending on the type of examination required, but as a rule it will take around 30 minutes. Read more about MRI here

In ultrasound, a beam of sound at a very high frequency (that cannot be heard) is sent into the body from a small vibrating crystal in a hand-held scanner head. When the beam meets a surface between tissues of different density, echoes of the sound beam are sent back into the scanner head. The time between sending the sound and receiving the echo back is fed into a computer, which in turn creates an image that is projected on a television screen. Ultrasound is a very safe type of imaging; this is why it is so widely used during pregnancy. Doppler Ultrasound A Doppler study is a noninvasive test that can be used to evaluate blood flow by bouncing high-frequency sound waves (ultrasound) off red blood cells. The Doppler Effect is a change in the frequency of sound waves caused by moving objects. A Doppler study can estimate how fast blood flows by measuring the rate of change in its pitch (frequency). A Doppler study can help diagnose bloody clots, heart and leg valve problems and blocked or narrowed arteries. What to expect? After lying down, the area to be examined will be exposed. Generally a contact gel will be used between the scanner head and skin. The scanner head is then pressed against your skin and moved around and over the area to be examined. At the same time the internal images will appear onto a screen. Read more about ultrasound here Read about pregnancy ultrasound here

A mammogram is a special type of x-ray used only for the breast. Mammography can be used either to look for very early breast cancer in women without breast symptoms (screening) or to examine women who do have breast symptoms (diagnostic). What to expect? You will need to undress from the waist up. One of your breasts will be positioned between two plastic plates which will flatten the breast slightly. Most women find that this is a bit uncomfortable, but not painful. Generally two x-rays are taken of each breast. It is also useful to compare the results with earlier examinations and you should take any previous mammography results with you. Read more about mammography here

DEXA (which stands for dual energy x-ray absorptiometry) scanning uses special x-rays to measure the density of your bones. The density of your bones will show how strong they are. The exposure to x-rays is very low and is similar to what you would receive on a long distance plane flight. What to expect? You will lie very still on a padded table for 5-10 minutes while the arm of the machine passes over the area to be measured (usually the lower spine and hip, although the forearm can also be measured). This is quite painless. You can remain in your normal clothing, although you may have to take off anything with large buttons, buckles or metal zips. Read more about bone densitometry and body composition here.

A specially trained technician performs this test. It is a test that uses high frequency sound waves to generate pictures of your heart. During the test, you generally lie on your back and gel is applied to your skin to increase the conductivity of the ultrasound waves. The technician then moves the small, plastic transducer over your chest. The test is painless and can take from 10 minutes to an hour. The machine then analyses the information and develops images of your heart. These images are seen on a monitor. This is referred to as an echocardiogram. Echocardiography can help in the diagnosis of many heart problems including cardiovascular disease, previous heart attacks, valve disorders, weakened heart muscle, and holes between heart chambers. If doctors are looking for evidence of coronary artery disease they may perform variations of this test which include Exercise echocardiography. This technique is used to view how your heart works under stress. It compares how your heart works when stressed by exercise versus when it is at rest. The ultrasound is conducted before you exercise and immediately after you stop. Either a stationary bicycle or standard treadmill is used. Dobutamine stress echocardiography. If you're unable to exercise for the previous test, you might be given medication to simulate the effects of exercise. During this test, an echocardiogram is performed when you're at rest. Then medication dobutamine is then given to you via a needle into a vein in your arm. Its effect is to make your heart work harder and faster just like with exercise. After it has taken effect, the echocardiogram is repeated and compared. The effects wears off very quickly. Read more about echcardiography here

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