Which of the following factors does NOT directly influence exposure rate?

The factor that does not directly influence the exposure rate is the quality of the image receptor. The exposure rate refers to the amount of radiation delivered per unit time to the patient or the image receptor during a fluoroscopic procedure. Factors such as milliampere (mA), filtration, and exposure time directly affect this rate by altering the quantity and quality of the radiation beam.

For instance, increasing the mA results in a higher current which enhances the number of x-ray photons produced, thus increasing the exposure rate. Filtration, on the other hand, removes low-energy x-rays from the beam, which can improve the quality of the resultant image while affecting the exposure received by the image receptor. Similarly, extending the exposure time allows more radiation to be delivered, increasing the exposure rate.

The quality of the image receptor impacts how efficiently the available radiation is converted into a diagnostic image but does not inherently alter the exposure rate itself. Therefore, while all the other factors directly modify the exposure rate, the quality of the image receptor does not have that direct impact.