Lesson 1, Topic 1
In Progress

Basic Radiation Safety

April 11, 2024

Basic Radiation Safety

Learning Objective: Examine basic radiation safety.

Radiation exposure may pose a health hazard to operators if proper safety precautions are not followed. The potential risk is greater for the operator than the patient because the operator is often faced with the possibility of exposure. Scatter radiation is present throughout the x-ray room during exposure. The only time the potential for exposure exists is when the x-ray exposure is taken.

Risks Associated with Radiation

Learning Objective: Describe the risks associated with radiation.

The general public does not sufficiently understand the health risks involved in radiation. Diagnostic radiography involves low doses of radiation, and the risks to both patients and limited operators are extremely small. It is essential to understand the risks associated with radiography and commit to radiation safety in all aspects of radiography work. When appropriately used, radiation from x-ray examinations also has benefits. The diagnostic information that the patient’s physician receives from the x-ray examinations far outweighs the risks of exposure.
Ionizing radiation consists of particles, X-rays, or gamma rays with sufficient energy to cause ionization in the medium through which it passes. Radiation protection aims to reduce unnecessary radiation exposure to patients and operators. The biological effect of radiation exposure varies according to the type of radiation involved, its energy, and the types of cells that are exposed. Also, some cells are more sensitive to radiation than others. The law of Bergonie and Tribondeau states that cell sensitivity to radiation exposure depends on the following characteristics of cells:

1. Age: Immature (or younger) cells are more sensitive than mature cells. Younger tissue and organs are also more sensitive.
2. Differentiation: Undifferentiated (or simple) cells are more sensitive than differentiated (or specialized) cells.
3. Metabolic rate: Cells with a higher metabolic rate are more sensitive.
4. Mitotic rate: Rapidly dividing cells are more sensitive.

Highly radiosensitive tissues and organs are at a higher risk of injury from radiation. These include:

• Bone marrow and blood: Serious changes can occur with these cells.
• Intestines and lymphoid organs, such as the spleen, thymus gland, and lymph node.
• Gonads, such as the testes and ovaries. Permanent damage can occur that results in genetic mutations and sterility. Genetic mutations can be passed to offspring.

Organs and tissues that have a middle-range radiosensitivity include the epidermis, hair, eye lens, lungs, thyroid gland, liver, and kidneys. Tissues with lower radiosensitivity include muscles, bones, nerves, and blood vessels.

Protection for the Operator

Learning Objective: Describe protective practices for the operator.

The sources of radiation are the x-ray tube and the patient, as a source of scatter. There is the possibility of exposure to the operator from either the primary x-ray beam or from scatter radiation from the patient. The three principal methods used to protect limited operators from unnecessary radiation exposure are time, distance, and shielding. Time and distance apply principally to radiographers who are involved in fluoroscopy and mobile radiography. Shielding is employed to protect all radiographers.
The amount of exposure is directly proportional to the time spent in the radiation field, so the occupational dose is decreased when this time is minimized. The next method is distance. The operator should increase the distance from yourself and the source of radiation. This will decrease exposure proportionately to the square of the distance. Therefore, a small increase in distance will reduce operator dose significantly. The final, and most common method of protection is shielding. The walls of the x-ray room contain lead to reduce exposure to the operator. Other types of shielding include lead aprons, gloves, and thyroid shields. If the operator must be in the room during exposure, it is essential to wear a protective lead apron.
The limited operator must wear a device to monitor exposure to ionizing radiation. This device, a personnel dosimeter, is required whenever a radiation worker is likely to receive 10% or more of the annual occupational effective dose limit of 50 millisieverts (mSv).


Critical Thinking Application

Stephanie has an x-ray request for a chest x-ray examination. She brings the patient, Mrs. Jones, into the room. During her assessment of Mrs. Jones, Stephanie realizes that Mrs. Jones will not be able to stand unassisted for the chest x-ray. Therefore, Stephanie will be in the x-ray room during the exposure. How can Stephanie protect herself from radiation exposure?

Protection for the Patient

Learning Objective: Describe protective practices for the patient.

The guiding philosophy is the ALARA principle. The ALARA principle states that all radiation exposure should be limited to levels that are “as low as reasonably achievable.” The limited operator can reduce radiation exposure to patients by reducing repeat exposures, using the smallest radiation field, using the highest kVP and the lowest possible mAs, and maintaining the source-to-image-receptor distance (SID) at a minimum of 40 inches.