What happens to radiographic density and scatter when the field size is decreased?

What happens to radiographic density and scatter when the field size is decreased?

• A. Decrease density and decrease scatter
• B. Increase density and increase scatter
• C. Decrease density and increase scatter
• D. Increase density and decrease scatter

Answer: (A)

Reducing the field size lowers both radiographic density and scatter because you irradiate a smaller volume of tissue. With less tissue being exposed, fewer primary photons are attenuated, and fewer photons reach the image receptor in total, so density decreases. At the same time, scatter is produced in the irradiated tissue, so less irradiated tissue means less scatter generated and fewer scattered photons reaching the detector. If you needed the same density with a smaller field, you’d have to increase exposure factors, which would raise patient dose.

Reducing the field size lowers both radiographic density and scatter because you irradiate a smaller volume of tissue. With less tissue being exposed, fewer primary photons are attenuated, and fewer photons reach the image receptor in total, so density decreases. At the same time, scatter is produced in the irradiated tissue, so less irradiated tissue means less scatter generated and fewer scattered photons reaching the detector. If you needed the same density with a smaller field, you’d have to increase exposure factors, which would raise patient dose.