X-ray imaging basics

Understanding the extent and location of abnormalities in anatomy and tissues is often a critical part of diagnosis for many diseases and injuries. In the past, surgery, physical pressure, and asking the patient "where it hurts" were the main accessible methods.

In many cases, radiologists can get the information needed for diagnosis indirectly, non-invasively, and with little discomfort to the patient by the use of a variety of medical imaging methods.

X-ray imaging is the oldest and perhaps also the most common indirect medical imaging method. Other methods of imaging include magnetic resonance imaging (MRI), ultrasound imaging (US), computed tomography (CT), and nuclear medicine including PET (positron emission tomography) and SPECT (single photon emission computed tomography).

The different imaging methods are best suited for different imaging tasks and are often complementary. For example, X-ray based techniques such as X-ray film images and CT-scans, image the differences in tissue and bone density. MRI shows good image contrast between various soft tissues. Ultrasound and fluoroscopic X-ray imaging can both be employed in real-time imaging to follow motion within the body. Nuclear medicine, PET, and SPECT can image function, for example the differential uptake of a drug between a tumour and surrounding healthy tissue.

Read about the discovery of X-rays (a historical synopsis of the last 100 years).