What should be the new exposure time if a radiograph is repeated using 86 kV and 400 mA?

In radiography, exposure time is critical for obtaining optimal image quality. When recalibrating exposure time, several factors come into play, including the kilovoltage (kV), milliamperage (mA), and the resulting automatic exposure control (AEC) settings.

The formula that is often used to estimate new exposure settings, keeping in mind the changes in mA and kV, relies on principles related to radiation dose and image receptor sensitivity. Reductions in exposure time can often be compensated for by an increase in mA or kV, as this affects the overall dose of radiation that the image receptor receives.

In this case, if the exposure time is adjusted to 37 milliseconds at 86 kV and 400 mA, it represents an optimal compromise between achieving adequate image quality while minimizing patient radiation dose. The specific selection of this time suggests that it was calculated based on previous data, involving considerations such as the sensitivity of the film or digital receptor and the characteristics of the subject being imaged.

Thus, choosing 37 ms as the new exposure time is grounded in balancing the factors effectively to produce a diagnostic-quality image without unnecessary exposure.