How is the patient's radiation dose altered when switching from a 6-inch magnification mode to a 9-inch mode?

Switching from a 6-inch magnification mode to a 9-inch mode affects the radiation dose received by the patient primarily due to changes in the distance from the radiation source to the patient and the magnification processes involved.

When increasing magnification, the source-to-image distance increases. Specifically, since the square of the distance from the source determines the intensity of the radiation reaching the patient, moving from a shorter distance to a longer distance (from 6 inches to 9 inches) leads to a reduction in dose. The inverse square law of radiation states that if the distance from the source is increased, the radiation intensity (and thereby the patient's dose) decreases.

To calculate the change in dose when moving from 6 inches to 9 inches, one would apply the inverse square law. The formula shows that the intensity (or dose) is inversely proportional to the square of the distance.

1. For 6 inches, the intensity factor is proportional to ( 1/(6^2) ), which is ( 1/36 ).
2. For 9 inches, it becomes ( 1/(9^2) ), which is ( 1/81 ).

When you compare these two factors, the ratio of