A kV and mA question

stutech · Joined: 02 Aug 2006 Posts: 29 Location: NC

1) If for an Ap ab for a UGI you set a manual technique at 70 kVp and 46 mAs and you introduce barium for the exam; what would your manual technique(mAs) change to if the kVp was changed to 110 for the oblique views of the stomach?

2) Why did you change the kV?

3) What is the advantage of changing the kV to 110 vs 90 as far as the pt is concerned?
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Guest · Posted: Sun Aug 06, 2006 12:29 am Post subject:

Gotta do so math with that problem.

stutech · Joined: 02 Aug 2006 Posts: 29 Location: NC

It's easy math though.
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The right angle to approach a difficult problem is the "try-angle"

xrayquilter · Power User Joined: 04 Jul 2006 Posts: 120 Location: Ohio

You change the kV because the barium is a positive contrast agent, which has a high atomic number, therefore absorbing more x-rays than the surrounding tissue. If you're increasing the kV, then you should decrease the mAs to maintain the same density as without the contrast. The advantage to changing the kV to 110 is that you reduce the mAs even more, reducing exposure time to the patient. Am I close Confused

stutech · Joined: 02 Aug 2006 Posts: 29 Location: NC

You are correct. You would half the mAs for every 15% or about every ten you go up in kV below 100 so the mAs would end up being halved four times equaling 3.
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The right angle to approach a difficult problem is the "try-angle"