For those of you that may need a refresher on these, instructions are below...
In dealing with fraction numbers, which some of you very well could see if dealing with older machines, all you do is divide the top number by the bottom number.
To calculate mAs, just convert the fraction to a decimal number like above, and then multiply it by the mA.
Now if the machine gives you milliseconds, which many newer machine do, you will have to convert millseconds to seconds before calculating the mAs.
Decimal places go like this:
In order to convert 1 second to milliseconds, all you do is move the decimal place. You would move the decimal place 3 spots to the right, which would give you 1,000 milliseconds. So 1 second equals 1,000 milliseconds. Since we're dealing with mAs (milli Amp SECONDS), you will need to know how to convert milliseconds to seconds before calculating the mAs. For instance:
Let's try a couple more:
From there you are able to calculate mAs by multiplying it by the mA.
If you have any questions, please let me know...and just a fyi, most machines now days TELL you what the mAs is. It's not like you will have to calculate the mAs while setting the techniques for a patient, but this is general radiology information and you will most likely see a couple on your ARRT exam.