kVp and x-ray Contrast (Guide for Radiologic Technologists)
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- čas přidán 6. 06. 2024
- The most important technical parameter for determining contrast is the kVp (kiloVolt peak). Lower kVp settings are preferred from the standpoint of image contrast, provided that enough x-rays can pass through (penetrate) the patient such that the image is not dominated by noise.
For more details on the physics behind radiology see our site: howradiologyworks.com . - Věda a technologie
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Thank God I found this video. I study radiography and currently struggling with Physics. You're channel is amazing and very informative! Thank you, Sir!
You’re welcome Kaori. Really appreciate your comments. Your only job now is to share with your classmates.
Brief yet truly informative!
Thanks
Such a well explained and helpful revision video than you so much 🌼🌼🌼
You’re welcome, thanks for dropping the comment
Such a well explained and helpful revision video than you so much
Glad to hear that! Thanks for the comment 😊
currently watching as i have a radiation physics exam due tomorrow, glad i found this channel, thank you so much respected sir
Good luck on the exam. Let me know if there is something on the test you can’t find on the channel to pay it forward
@@HowRadiologyWorks Dear sir, thanks for your best wishes, the exam went well and this channel is for sure a treasure i will cherish , i have found everything that i needed so far on this channel and am really glad for your help
@@devduttupadhyay04 awesome to hear it. Thanks for the well wishes and glad that the exam went well. Good luck in the rest of your courses.
If you have a high REX number and a low exposure index number would this be due to a high kVp?
Thank you for your good information.❤️❤️
You are so welcome medical services😉
Good explanation 👍
Thanks Asela, glad you liked it. Share with your colleagues.
Good explanation sir
Thanks Ramji
I am extremely confused, how can we use higher kVp values in barium enema alone?!
Isn't it supposed to the photoelectric effect to predominate at higher atomic number msterial, k edge for barium 37 so we should be using lower kVp values 🤯
In regards to using 50 kVp for a hand; I wouldn't use less than 60 kVp for anything on an adult size person with digital imaging. Since contrast is adjustable on the display, use as high a kVp as will not overpenetrate the part, and reduce the mAs to reduce ESE while maintaining IR exposure at the level that results in a high quality image.
radiopaedia.org/articles/hand-bilateral-pa-view-1?lang=us , thanks for your comment yeah right in that range is good and Radiopedia recommends 50-60kVp. If you have a hand phantom you can figure out for your system what kVp gives you optimal CNR. It should be in that range.
To highlight bone structure Kvp and mAs are adjusted. How much more radiation does that expose to patients? E.g., typical chest x-ray standard is 0.02-0.04 mSv.
The kVp is adjusted before the exam and the mA is selected before and the time may be set manually or using automatic exposure control. So the selection of parameters is not extra exposure
Hello, one of the quiz questions on the ARRT prep website Corectec seems to contradict the teaching that kVp affects contrast. I'm hoping you can tell me if the website is in error or offer clarification. The quiz question says:
_"In order to achieve an exposure as low as reasonably achievable, which of the following changes can be made with digital imaging WITHOUT changing the brightness or contrast?"_
According to the website, the correct answer is this:
_"Increase kVp, decrease mAs"_
Is this really saying that increasing the kVp doesn't change contrast? I thought higher kVp resulted in a longer scale of contrast. There must be some nuance here that I'm not grasping.
Yes there is some subtleties that they are considering digital imaging of soft tissue. If the exam was to look at a contrast enhanced region I believe the optimal kVp would be lower. So I believe the question should say with minimal change in contrast, rather than without. Feel free to submit a question to that team for clarification as well but this is my interpretation. I do agree that with digital processing the kVp selection becomes less impactful.
@@HowRadiologyWorks I see. Thank you for the reply
According to the ARRT, kvp is not considered the main controlling factor for contrast in digital radiography. Computer processing factors like the LUT and window width are. That’s not to say kVp plays no part in contrast, but compared to film, its influence is significantly less.
@@AngEP78thanks for the comment. Yes I believe that is consistent with what I mentioned above that kVp has less impact than before but I don’t think it’s correct to say no impact as the question posed. Thanks again
How would you determine kVp and mAs for mobile chest radiographs?
Mobile x-ray is similar to traditional x-ray where the body part will dominate the optimal technique. Did you have a specific body part in question?
@@HowRadiologyWorks chest xrays done on a mobile unit.
Good subject excellent what about mas
Good idea Harout. I will make another video on mas relatively soon. It seems I can only keep peoples attention for a few minutes so separating out to smaller videos.
Can u please do anything on Mammography machine. Or guide me to be more knowledgeable
6:30 typo: Penetration*
Thanks I should have copied it from the previous slides I guess
I’ve never shot a hand above 65kv. Who uses 70+ kv on an extremity?
Yes you are right in extremities I was including shoulders also that are typically in the 70s but hands would typically be in the 50s. Thanks for the clarification