If object-to-image distance increases while SID remains constant, magnification will:

If object-to-image distance increases while SID remains constant, magnification will:

• A. Decrease
• B. Increase
• C. Stay the Same
• D. Vary

Answer: (B)

Magnification in radiography changes with geometry: the magnification factor is determined by the distance from the source to the image receptor (SID) divided by the distance from the source to the object (SOD). If SID stays the same and the object-to-image distance increases, the source-to-object distance must decrease, making the denominator smaller. That makes the magnification factor larger, so the image appears bigger. Intuitively, as the object moves away from the image receptor toward the X-ray tube, the divergent beams spread more before hitting the receptor, enlarging the projection. Conversely, bringing the object closer to the receptor would reduce magnification.

Magnification in radiography changes with geometry: the magnification factor is determined by the distance from the source to the image receptor (SID) divided by the distance from the source to the object (SOD). If SID stays the same and the object-to-image distance increases, the source-to-object distance must decrease, making the denominator smaller. That makes the magnification factor larger, so the image appears bigger. Intuitively, as the object moves away from the image receptor toward the X-ray tube, the divergent beams spread more before hitting the receptor, enlarging the projection. Conversely, bringing the object closer to the receptor would reduce magnification.