X-rays are produced when charged particles (electrons or ions) of sufficient energy hit a material and are suddenly decelerated upon their collision.
X-ray images are produced when a patient is placed in front of an X-ray detector and is then illuminated by short X-ray pulses. X-rays are absorbed by dense material with high atomic number such as bones, which are rich with calcium, and appear white on the resulting image. In the other hand, material with low or no atomic number, such as air in lungs, show up as dark patches on X-ray images because of their low absorption rates.
Type of X-Ray:
There are mainly 3 types of clinically used X-ray:
Radiography is the most familiar type of X-ray imaging. It is used to image mainly bones and the chest. Radiography also uses the smallest amounts of radiation.
Fluoroscopy is continuous live use of X-ray, and cane considered as a movie equivalent. The radiologist can watch the X-ray of the patient moving in real-time to watch the activity of the gut after a barium meal or intravascular contrast. Fluoroscopy uses more X-ray radiation than a standard X-ray, but the amounts are still tiny.
During Computed tomography (CT), the patient lies on a table and enters a ring-shaped scanner. A fan-shaped beam of X-rays passes through the patient into detectors placed across the patient’s body. The patient moves slowly into the machine so that a series of slices can be taken. This procedure uses the highest dose of X-rays because so many images are taken in one sitting.
The risk of X-Ray:
X-rays can cause mutations in the patient’s DNA and, therefore, might lead to cancer later in life. For this reason, X-rays are classified as a carcinogen by both the World Health Organization (WHO) and the US government. However, the benefits of X-ray technology far outweigh the potential negative consequences of using them. It is estimated that 0.4% of cancers in America are caused by CT Scan and this level is expected to rise in parallel with the increased usage of CT scans in medical procedures.
Each procedure has a different risk associated with it, depending on the type of X-ray and the part of the body being imaged. In example:
- Chest X-ray is equivalent to 2.4 days of natural background radiation
- Lumbar spine is equivalent to 182 days of natural background radiation
- Upper gastrointestinal barium exam is equivalent to 2 years of natural background radiation
- CT head is equivalent to 243 days of natural background radiation
- CT abdomen is equivalent to 2.7 years of natural background radiation.
Even though the X-ray has been associated with risk of cancer, their benefit if used properly surpass their claimed danger: the importance of making the right diagnosis and choosing the correct course of treatment makes X-rays far more beneficial than they are dangerous.
Whether there is a small risk or no risk at all, the X-rays are here to stay.
Wessam Bou-Assaly is a highly experienced radiologist in Michigan with long years of practice.