How is receptor exposure affected by the selected SID?

How is receptor exposure affected by the selected SID?

• A. Directly proportional to the square
• B. Directly proportional
• C. Inversely proportional to the square
• D. Inversely proportional

Answer: (C)

The relationship between receptor exposure and the source-to-image distance (SID) is governed by the inverse square law, which states that the intensity of radiation (and thus the receptor exposure) is inversely proportional to the square of the distance from the radiation source.

When the SID increases, the radiation beam spreads over a larger area, resulting in decreased intensity and, consequently, lower receptor exposure. Conversely, when the SID is decreased, the radiation intensity at the receptor increases, resulting in higher receptor exposure.

This principle is critical for radiographers to understand, as it influences the adjustment of exposure factors to optimize image quality. Proper application of this concept ensures that images are neither underexposed nor overexposed, which is vital for accurate diagnostics.