National Board Dental Hygiene Examination (NBDHE) Dental Hygienist Practice Test

If the cone on the x-ray machine is increased in length, what happens to the radiation absorbed dose?

1. It increases

2. It decreases

3. It remains the same

4. It fluctuates

The correct answer is: It decreases

Increasing the length of the cone on an x-ray machine primarily serves to reduce the divergence of the x-ray beam. As the beam travels a longer distance, the intensity of the radiation decreases due to the inverse square law, which states that the intensity of radiation is inversely proportional to the square of the distance from the source. As a result, with the longer cone length, the radiation that reaches the film or detector becomes less concentrated, leading to a decrease in the amount of radiation absorbed by the tissues. This effect minimizes patient exposure and can enhance image quality by reducing scatter radiation. Understanding these principles is crucial for optimizing x-ray techniques and ensuring patient safety in dental radiography.