If magnification factor equals SID/SOD and SID is 50 inches with a magnification of 1.25, what is the SOD?

If magnification factor equals SID/SOD and SID is 50 inches with a magnification of 1.25, what is the SOD?

• A. 30 inches
• B. 50 inches
• C. 45 inches
• D. 40 inches

Answer: (D)

In radiography, the magnification factor tells us how much larger the image is compared to the actual object, and it relates to distances along the beam: M = SID / SOD. With a source-to-image distance (SID) of 50 inches and a magnification of 1.25, you solve for the source-to-object distance (SOD) by rearranging the formula: SOD = SID / M = 50 / 1.25 = 40 inches. This means the object sits 40 inches from the x-ray source, leaving an object-to-image distance (OID) of SID − SOD = 10 inches. A magnification greater than 1 indicates the image is larger than the object because the object is between the source and the image receptor.

In radiography, the magnification factor tells us how much larger the image is compared to the actual object, and it relates to distances along the beam: M = SID / SOD. With a source-to-image distance (SID) of 50 inches and a magnification of 1.25, you solve for the source-to-object distance (SOD) by rearranging the formula: SOD = SID / M = 50 / 1.25 = 40 inches. This means the object sits 40 inches from the x-ray source, leaving an object-to-image distance (OID) of SID − SOD = 10 inches. A magnification greater than 1 indicates the image is larger than the object because the object is between the source and the image receptor.