Similar to visible light, X-rays are a form of electromagnetic radiation. But x-rays have higher energy and can pass through most objects (also the human body). Images of tissues and structures inside the body are generated in medical x-rays. An image will be formed that represents the “shadows” formed by the objects inside the body while x-rays travelling through the body also pass through an x-ray detector on the other side of the patient.

There are many types of x-ray detectors used to produce digital images. One type of x-ray detector is photographic film. These images are called radiographs.

A patient is positioned in front of x-ray machine so that the part of the body being imaged is located between an x-ray source and an x-ray detector to create a radiograph. X-rays travel through the body and are absorbed in different amounts by different tissues, depending on the radiological density of the tissues they pass through when the machine is turned on. Radiological density is determined by both the density and the atomic number (the number of protons in an atom’s nucleus) of the materials being imaged. E.g., structures such as bone contain calcium, which has a higher atomic number than most tissues and that’s why bones readily absorb x-rays and, thus, produce high contrast on the x-ray detector. Bony structures appear whiter than other tissues against the black background of a radiograph as a result. X-rays travel more easily through fat and muscle, as well as through air-filled cavities such as the lungs (less radiologically dense tissues). These structures are displayed in shades of gray on a radiograph.

Diagnostic:

X-ray radiography: Broken bones, pneumonia, tumours and other abnormal masses, calcifications, foreign objects, dental problems, etc are detected through this.

Mammography: A radiograph of the breast that is used for cancer detection and diagnosis. Tiny bits of calcium, called microcalcifications are also detected through mammogram, which show up as very bright specks.

CT (computed tomography): A series of cross-sectional images of the body that can later be combined to form a three-dimensional x-ray image are generated by combining traditional x-ray technology and computer processing. Images got in CT are more detailed than plain radiographs and give doctors the ability to view structures within the body from many different angles.

Fluoroscopy: Real-time images of movement within the body or to view diagnostic processes (following the path of an injected or swallowed contrast agent) are generated by using x-rays and a fluorescent screen. It is used to view the movement of the beating heart, to view blood flow to the heart muscle as well as through blood vessels and organs. This technology is also used in angioplasty, which is a minimally invasive procedure for opening clogged arteries that supply blood to the heart.

Therapeutic

Radiation therapy in cancer treatment: Cancerous tumours and cells can be destroyed using X-rays and other types of high-energy by damaging their DNA. The radiation dose used is much higher for treating cancer than the radiation dose used for diagnostic imaging.

The benefits of x-ray scans are significantly higher than the risks when used appropriately. X-ray scans are used to diagnose possibly life-threatening conditions such as blocked blood vessels, bone cancer, and infections. Although, ionizing radiation is produced in x-ray —that is potentially harmful to living tissue. This risk can increase over time with number of times x-ray is used on an individual. Chance of developing cancer is too less though.