Question

You are performing a mobile chest x-ray. You have a distance of 60" and you use 6.3 mAs. How would you adjust your mAs value if you changed the distance to 72"?

Answer 1

When changing the distance from 60" to 72" in a mobile chest x-ray, the mAs value should be adjusted. The new mAs value can be calculated using the equation mAs_new = mAs_old * (D_old^2 / D_new^2), which gives a result of 4.375.

Step-by-step explanation:

When the distance is changed from 60" to 72", the mAs value should be adjusted to compensate for the change in distance. The mAs value is directly proportional to the distance squared, so to find the new mAs value, we can use the following equation:

mAsnew = mAsold * (Dold2 / Dnew2)

Plugging in the values, we get:

mAsnew = 6.3 * (602 / 722)

mAsnew = 6.3 * 3600 / 5184

mAsnew = 4.375

Therefore, if the distance is changed from 60" to 72", the new mAs value should be 4.375.