Question

An exposure was made using 600 mA and 18 ms. If the mA is changed to 400, which of the following exposure times would most closely approximate the original radiographic density?

1. 16 ms
2. 0.16 second 3. 27 ms 4. 0.27 second
Answer:
27 ms

Answer 1

To maintain the same radiographic density when the mA is changed, an exposure time of 27 ms would closely approximate the original radiographic density.

Step-by-step explanation:

To determine which of the given exposure times would most closely approximate the original radiographic density, we can use the concept of milliampere-seconds (mAs). mAs is a product of milliamperes (mA) and the exposure time in seconds (s). The original mAs value can be calculated as 600 mA multiplied by 18 ms, which equals 10,800 mAs. To maintain the same radiographic density, we need to find an exposure time that, when multiplied by a new mA value of 400, is close to 10,800 mAs. The closest option is 27 ms, as 27 ms multiplied by 400 mA equals 10,800 mAs.