An x-ray examination is used to create images of your internal organs or bones to help diagnose conditions or injuries. A special machine emits (puts out) a small amount of ionising radiation. This radiation passes through your body and falls on a film or similar device to produce the image.
The dose of radiation you will receive depends on the area of your body being examined. Smaller areas such as the hand will receive a lesser dose, compared to a larger area such as the spine. On average, the dose of radiation is roughly the same as you would receive from the general environment in about one week.
Tell your doctor if you are pregnant or think you may be pregnant. Another type of test may be recommended.
How X-rays Work
A tiny amount of ionising radiation is passed through the body. In the past, this went onto a sheet of special film. Nowadays x-ray examinations are more likely to use a device that will capture transmitted x-rays to create an electronic image.
The calcium in bones blocks the passage of radiation, so healthy bones show up as white or grey. On the other hand, radiation passes easily through air spaces, so healthy lungs appear black.
When X-ray Examinations Are Used
This test is very common. About seven million x-ray examinations are made every year in Australia. Some of the many uses include:
- diagnosis of fractures – detection of broken bones is one of the most common uses of this test
- diagnosis of dislocations – an x-ray examination can reveal if the bones of a joint are abnormally positioned
- as a surgical tool – to help the surgeon accurately perform the operation. For example, x-ray images taken during orthopaedic surgery show if the fracture is aligned or if the implanted device (such as an artificial joint) is in position. X-rays may also be used in other surgical procedures for the same purpose
- diagnosis of bone or joint conditions – for example, some types of cancer or arthritis
- diagnosis of chest conditions – such as pneumonia, lung cancer, emphysema or heart failure
- detection of foreign objects – for example, bullet fragments or swallowed coins.
Medical Issues With X-ray Examinations
- Tell your doctor if you are pregnant or think you may be pregnant. Another type of test may be recommended.
- A conventional x-ray examination does not require any special preparation.
- Some x-ray examinations involve the use of an iodinated contrast agent (a type of dye). This substance helps to improve the detail of the images or to make it possible to see body structures such as the bowel or blood vessels. The hospital x-ray department or private x-ray clinic will give you instructions on how to prepare for the test and what to expect.
- X-ray examinations can only detect severe cases of osteoporosis. Your doctor may suggest other tests to help confirm the diagnosis.
X-ray Examination Procedures
Depending on the part of your body being examined, you may be asked to undress, remove all jewellery and wear a hospital gown. The basic procedure then involves:
- You will either stand up or lie down on an examination table, depending on which part of your body is being investigated.
- The radiographer will place you between the x-ray machine and the imaging device that captures the x-rays being transmitted through that part of your body.
- The radiographer may shield parts of your body with a lead apron. This is to reduce the risk of unnecessary exposure to radiation.
- The radiographer will need to touch you in order to position your body correctly for each picture.
- The radiographer operates the controls while each image is taken. To do this, they will stand behind a screen and call instructions to you if necessary.
- You may be asked to hold your breath for a couple of seconds as each picture is taken, so that the breathing movement doesn’t blur the images.
- A straightforward and conventional x-ray examination of the hand, for example, usually takes a few minutes. Other types of x-ray examination may take longer.