What happens to the radiographic image when the end of the PID is pulled away from the patient's face by about 6 inches?

When the position indicating device (PID) is pulled away from the patient's face by about 6 inches, the radiographic image will appear lighter. This occurs because the X-ray beam will diverge as it travels from the source to the film or sensor. As the distance between the PID and the patient increases, the intensity of the X-ray beams reaching the film 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.

This means that when the PID is moved further away, fewer X-ray photons are focused on the film or sensor, leading to decreased exposure and a lighter image. Consequently, while the area being exposed may appear larger due to the diverging beam, the overall image becomes lighter because of the reduced number of photons reaching the sensor. Understanding this principle is crucial for accurately interpreting radiographic results and optimizing the quality of diagnostic images.