방사선 엑스레이 사진이 검을때 kvp, mas 조절...펌

* 통과해야할 환자의 몸의 두께는 kvp로 해결. 너무 세면 모두 필름에 도달. 너무 약하면 모두 몸에 흡수.

* 뼈는 하얗게 연부조직도 잘 보이게 할려면 mas 낮춤.  너무 많으면 필름에 너무 많이 도달, 적으면 몸에 다 흡수 필름에 도달하지 않음.

뚱뚱해서 희게나오면 kvp올림.

체격과 관계없이 연부조직이 검으면 mas를 낮춤.

희미하고 검을때, kvp, mas 다 낮춰볼수 있음.

* kvp를 올리고 mas를 낮출수록 환자 피폭이 덜됨.

 

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사진 농도는 Kvp와 mas 모두 연관이 있습니다.

Kvp나 mas를 올리면 사진이 검게 나오지만 양상을 조금 다릅니다.

Kvp는 주로 투과도를 결정합니다.

만약 Kvp가 낮아서 희게 나온경우 mas만 올릴경우 연부조직은 더 검게 나오나 뼈 부위는 여전히 하얗게 나오게 되고, 연부조직과 뼈조직의 농도차이가 커집니다.

찍는 부위별로 적절한 투과가 될수 있는 Kvp를 선택하시고, 다음으로 농도를 조절하기 위해서 mas를 조절하십시오.

환자가 뚱뚱해서 사진이 희게 나온 경우는 Kvp를 높여서 투과를 증가시켜야 하고, X-선 양이 부족해서 희게 나온경우는 mas를 증가시켜야 합니다.

요즘 가슴사진은 전용필름을 쓰거나, PACS 시스템을 주로 쓰게 되는데, 고관전압 촬영이 일반적입니다.

Kvp는 120 으로 고정하시고, 농도는 mas로 조절하시면 됩니다.

 

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Kristen M

 

Best Answer - Chosen by Asker

kVp affects penetration and mAs is the quantity of x-ray, so if you don't have enough penetration, you are going to have MORE absorbed dose because less xray is actually getting through the body. If you increase FFD, this also gives you less penetration, giving more absorbed dose if you do not increase your kVp, and if you decrease collimation, you will have more scatter which will give you more absorbed dose. SO, in effect you have
increase kVp=decrease absorbed dose
increase FFD=increase absorbed dose
 increase collimation=decrease in absorbed dose. Hope this helps!

Source(s):

I used my memory, but you could probably look it up in Fuch's or a radiation physics book.

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Best Answer - Chosen by Voters

kVp and mAs are controls you adjust at the console
 density and contrast are things on the x-ray that are adjusted by the above as well as other factors like what part you're x-raying
 
mA and mAs= same. s = seconds so you just multiply them
 
Contrast = difference between white and black on film. If an x-ray, like a hand x-ray, has a big difference between the white and blacks and has a short scale (aka hardly any shades of grey) on it, it has a high contrast. An abdomen x-ray has many shades of grey and therefore has low contrast and a long scale of contrast.
 High contrasthttp://www.shutterstock.com/pic-51884233…
 low contrast (first x-ray)
 https://online.epocrates.com/u/2911995/I…
 
see the difference?
 
Kilovoltage is related to contrast. As kVp increases contrast decrease. As kVp increases the energy of the electrons in the x-ray tube increasing both the energy of the x-ray beam and the probability that more electrons will produce x-rays. If the x-ray energy increases the x-rays can penetrate more anatomy and more beams hit the film all around, causing everything to get darker, therefore there is less contrast probably making it a low contrast film. As kVp decreases contrast increases. on the other hand, if the kVp is low, lower energy x-ray beams will be produced and more will be absorbed on its way to the x-ray film.
 kVp also affects density but on a much lower scale than mAs (which I will explain in a second). But just keep this in mind.
 kVp is the primary factor for contrast
 
Density - It is important to realize that density can be referring to two things, the density of the anatomy and the density of the film. If contrast is used hand in hand (like your question) than it is referring to density on the film. The other density is how dense: the anatomical number a substance is such as bone. If something on an x-ray is very light, or white, you would say it has low density. Something such as air in the stomach that would appear black on an x-ray would have high density.
 In this picture the lungs have a high density and the surrounding tissues, the heart, and the ribs have low density
 http://www.flickr.com/photos/aidan_jones…
 
mAs - mAs (or mA) is the prime factor in controlling density. mAs controls how many electrons are produced at the cathode. The more electrons produced at the cathode the more x-rays that will be produced at the anode. The more x-ray beams then more x-rays will hit at each part of the x-ray where it was already hitting. Since mAs has nothing to do with the energy of the beam it won't penetrate any different parts of the body, just make the parts it already is darker.
 This is more in a sense that if you don't have enough x-rays at all, despite the kVp, the x-ray will be too light due to not enough x-ray beams hitting the film anywhere.
 
Overpenetrated (first picture) too dark because you want to see details of the bronchial tree in the lung
 http://www.ask.com/wiki/Abdominal_hernia
 
Underpenetrated
 http://www.arrs.org/education/cert/demo2…
 
If you do one or the other you are losing anatomy information.
 

If you have any other questions or need further explainations just let me know!

Source(s):

X-ray technologist