In magnification fluoroscopy, which input phosphor field size delivers the lowest patient dose?

In magnification fluoroscopy, using a larger input phosphor field size, such as a 30 cm field, is associated with delivering a lower patient dose compared to smaller field sizes. This is because a larger input phosphor allows for a wider area of the patient to be imaged, which can be achieved with lower radiation exposure due to the geometry of the system and the ability to use lower mA settings while still maintaining adequate image quality.

Additionally, larger field sizes improve the efficiency of photon detection. The more extensive area means that the amount of scatter radiation is relatively reduced, allowing the system to rely on a greater proportion of primary radiation from the source without increasing patient exposure significantly.

In comparison, smaller field sizes necessitate higher radiation doses to provide adequate imaging due to increased magnification, which can lead to diminished image quality if the dose is not increased appropriately.

Thus, a 30 cm field optimally balances the advantages of reduced dose and the maintenance of image quality, making it the most favorable choice for minimizing patient exposure in magnification fluoroscopy.