Archive for November, 2010

Understanding the Workings of X-rays

November 2, 2010

X-rays are used in podiatry for many reasons. For example, X-ray can be used to monitor the healing progress of a surgical procedure, confirm a suspected fracture or to confirm a bone infection. In other words, X-ray images are tools to assist and improve patient care. There are, however, potential harmful effects of X-ray radiation. Therefore, the process of taking X-rays and common precautions must be understood.  With an understanding of the mechanism and nature of X-ray concerns, potential negative effects can be lessened.

Properties of X-rays:

The nature of X-rays can be perplexing because it is a form of energy similar to light. However, unlike light, there is nothing directly or physically seen. A main component in creating X-ray images is radiation, which is the transmission of energy as waves or particles akin to light. There are different types of radiation, ranging from lower energy radiation like radio, television, microwaves, and visible light to higher energy radiation like X-rays. Unlike low energy waves, X-ray radiation can change the properties of particles of an object that are exposed to the high-energy emission.

Categorizing X-ray Radiation:

There are three categories of radiation that are found where X-ray radiation is used.

The strongest is called the primary beam. This is the radiation that is made inside the X-ray tube which is located in the X-ray machine. The tube is made of glass that is lined with lead. This is meant to contain the X-ray waves and prevent X-ray overexposure to the patient and personnel that are near the machine. The primary radiation exits the tube and is directed toward the area of the patient being examined.  Of the three categories of X-ray radiation, primary radiation is the most dangerous and most intense.

The second type of X-ray radiation is referred to as secondary radiation, made of scatter or leakage radiation. Scatter radiation comes mostly from the patient when the primary beam is reflected off of the patient’s body. This type of radiation emission is most dangerous to personnel in the room. Leakage radiation is the energy waves that escape out of the X-ray tube.

The final and third category of X-ray radiation is remnant radiation, which is the energy waves that exit the patient and produces the image on the film.

Potential Dangers of X-ray Radiation:

X-ray radiation passes through body tissue and has enough energy to change the genetic make-up of cells that make up the tissues in the body. This can result in the overgrowth of cells. Of all the organs in the body, the lens of the eyes, sexual organs, white blood cells, and the thyroid gland are most sensitive to X-ray radiation. However, it takes an exceedingly large amount of radiation to damage the genetic components of cells and tissues.

In the case of pregnant women, the brain and spinal cord of the fetus is most sensitive to radiation and thus X-ray exposure is avoided during the 10th to 17th week of pregnancy. This time period corresponds to the growth period of these structures in the developing child. There are industry-accepted doses of radiation that can be exposed to a patient and rarely, if ever, does the amount of X-ray radiation performed exceed the maximum amount. In podiatry, it would require 5,000 X-ray exposures to be considered harmful to a pregnant woman, and this number is even higher for non-pregnant patients. Despite research showing low-risk from X-ray radiation, precautions and safety procedures are still practiced to fully protect the patient from potential damages.

Protection from X-ray Radiation:

There are two main forms of protection against overexposure of X-ray radiation, distance and shielding. Increased distance between a person and the X-ray machine decreases the amount of exposure to X-ray radiation. This is important for health care personnel, who frequently administer X-ray imaging.

The second form of protection against radiation is shielding. Commonly, a lead apron is worn by the patient to protect against unnecessary exposure to radiation to other parts of the body.

What to Expect When Taking X-rays:

A state certified radiology healthcare personnel places the lead apron on the patient. If the patient is female of childbearing age, she will be asked if she is pregnant. Then the strength of the X-ray beam is adjusted. Next the body part being studied will be correctly positioned. The person taking the X-ray will make sure everyone has cleared the area. A button is pushed to take the image accompanied by a buzzing sound. This sound indicates that the image is taken. In podiatry, there are at least two images taken for each X-ray study. The reason for this is that the foot is a three-dimensional object, but X-ray images are only a two-dimensional representation of the foot. Therefore, more than one X-ray view is needed to provide the podiatrist with a better visualization of the possible problems in the feet. Once the film has been processed, the film will have areas of black, which represent the soft tissues.  The X-ray beam has passes through these areas of the body and strikes the film or sensor at near full strength causing these areas to become fully exposed and appear black.  The image will also have areas that appear white. This represents areas where X-ray beams are stopped and absorbed therefore they do not reach the film or sensor. This occurs when the X-ray strikes hard tissue such as bone.