If the original exposure setting is 400 mA at 70 ms, which setting would maintain the receptor exposure if the mA is increased to 500 mA and kV to 90?

To determine the correct exposure time that maintains the receptor exposure when adjusting the milliampere-seconds (mAs) by changing both the milliamperes (mA) and kilovoltage peak (kVp), it's important to understand how these parameters relate to the overall exposure to the imaging receptor.

Initially, the exposure can be calculated as follows:

1. Original mAs Calculation: The original condition of 400 mA at 70 ms gives us the original mAs:

[

\text{Original mAs} = 400 , \text{mA} \times 0.070 , \text{s} = 28 , \text{mAs}

]

2. New mA Setting: When the mA is increased to 500 mA, we need to calculate what exposure time is required to keep the same mAs:

To maintain the same receptor exposure, you want to keep the mAs the same when changing the mA setting:

[

\text{New mAs} = \text{New mA} \times \text{New time}

]

Setting the new mAs equal to the original:

\