mAs radiography (Radiologic Technologist Guide)

mAs in radiography is the product of tube current (mA) and time (s): mAs=mA*s .
The tube current is the flow of electrons hitting the anode in the x-ray tube where the x-rays are generated. The mA is proportional to the number of x-rays coming out of the tube. The time that the beam is on in seconds is also proportional to the number of x-rays produced.
Therefore, the exposure is directly related to the mAs and we describe in this video how the desired settings of the technical parameters will be to first fix the: Bucky, SID, kVp and then use the mAs to control the exposure.
For more information on the physics of radiology see our website: howradiologyworks.com.

[@lisagallegos4811]

I love this video. I was struggling understanding the differences between KeV, kVp, mA, and mAs

[@HowRadiologyWorks]

Make sure to see our video on kVp too

[@dannalivingston7840]

Thank you so much, I'm studying for my exams now and these are very helpful. A little side note - it's fun seeing your son in the videos! Keep up the great work, it's much appreciated!

[@TheNettforce]

Thanks Danna. Appreciate the kind words.

[@TheNettforce]

My older son is too cool now so not sure how much longer I have

[@Meedan7]

Superb explanation and example with the water and cup analogy

[@HowRadiologyWorks]

Thanks for taking the time to drop the comment, much appreciated

[@abdovitamins6331]

Still revising your videos ❤

[@HowRadiologyWorks]

thanks lots to get through

[@haroutzeitounian4187]

Great thanks for this video god bless you brother

[@HowRadiologyWorks]

Thanks for the request, I think others will appreciate it as well

[@nonahs1487]

God bless you, sir. I’m a senior radiology resident and I’ve been struggling to understand the difference between kVp, mA and other basics of physics ever since I was R1. Thank you so much 🙏🏻

[@HowRadiologyWorks]

Glad it was helpful Nonah, share with your resident friends 😉

[@ranjanvk2199]

That's help us very much❤love from india

[@HowRadiologyWorks]

Thanks Ranjan for the comments. Glad it reaches you over in India

[@authman-alshibly]

How's mA related to organ types, penetration, contrast, and spatial resolution? And what makes us decide on whether to choose lower mA and higher time or the opposite?

[@TheNettforce]

Authman the first decision to make is the kVp which determines the contrast and penetration (see our kVp video) and yes we discuss the organ dependence in there. Then the mAs is used to fine tune the tolerable noise to in the image. The high contrast spatial resolution (as measured by MTF see our video) is not dependent on the mA but for low contrast tasks the mA will limit visibility which is the point we were going for in this video on mA.

[@authman-alshibly]

@@TheNettforceThank you so much.
I appreciate the explicit explanation.
I will watch all the videos and let you know if I have further inquiries.

[@TheNettforce]

@@authman-alshibly you’re welcome, yeah let me know if anything isn’t clear.

[@gustavofoss2280]

hey there, great video, but the interactive calculators aren't working properly on your webpage.

[@HowRadiologyWorks]

Try it now. I just did an update so should be working now. Thanks for letting me know it was down.

[@makq3151]

Please make a vidio on rotation in chest x ray and it's consequences..

[@HowRadiologyWorks]

Do you mean geometric effects like forshortening?

[@sophiejane1700]

Hi, could you explain why in a chest x-ray the mAs is so low when the kVp is so high? I can't seem to get my head around this

[@HowRadiologyWorks]

We have a video on kVp as well, make sure to check it out. The kVp will be lowered for iodine and barium imaging and bone imaging. Since these chests are often focused on soft tissue and air the is not a big driver for low kVp. At high kVp there is less absorption in the tissues so the dose is lower. Then after the kVp is fixed we select the mAs based on the noise in the image. Since there is a lot of air in the chest it is less attenuation and so the mAs can be lower.

[@vinceiodice824]

@@HowRadiologyWorks
why is there less absorption in the tissues at high kVp and therefore the dose is lower? I really can't understand this since high kVp means more penetrative power

[@TheNettforce]

@@vinceiodice824 we am x-ray penetrates it does not stop in matter and does not deposit dose so high penetration means lower dose deposited

[@eyasutekle2553]

@@vinceiodice824 The absorption dose depends on density of the body and on the amount of kVp. Kvp is something that gives energy for electrons to pass through. So, if we increase the kVp the radiation gets energy to penetrate and helps to get through. As a result, the dose of radiation a patient absorbs will be smaller and it's less likely to cause harm.

[@meyowmeyow1205]

The best

[@HowRadiologyWorks]

Awesome. I feel like David on Schitt’s Creek.

[@user-bk7bc2yb2h]

HELLO SIR . HELP PLESE -TRILP-TR300A RADIOGRAPHIC X-RAY UNIT-KeV, kVp, mA, and mAs

[@HowRadiologyWorks]

Can you write the question on a little more detail?

[@nexusSix_237]

Ray Romano

[@HowRadiologyWorks]

I wish

[@JyotiKumari-bb7tu]

Please sir ji in Hindi video 👍💖🙏

[@TheNettforce]

What is JI in this context?