Відео

Tanu, please edit your question and repost it. It is mixed with a different language I cannot understand. If your question is physics based and not medical in nature I can try to give you an answer.

@@ozoagali sorry but my question is medical in nature

no problem! Hope you can get the right answers from a medical professional. Good luck.

Blake, I’m not sure I fully understand your question, but I hope my answer can guide you. It seems to me that you are mixing several concepts here. It is true that in mammography we want a lower KV compared to general radiography. This is to take advantage of more photoelectric interactions at lower KVs relative to Compton interactions. In mammography both 27KV and 29KV are well within the range where photoelectric interactions are dominant over Compton interactions, so the advantage is not lost in going from 27 to 29KV. Now, when you talk about DQE, keep in mind DQE is on the receptor side not on the tube side. It is a frequency dependent metric and describes how well a particular imaging system (image receptor) processes both signal and noise. When you say two mammography data do you mean data from two different machines or is it the same machine with exposures taken at 27KV and 29KV? This part of my answer assumes you have 27KV and 29KV data from the same machine. In this case when a higher KV is used the tube output is higher, so the noise is less. DQE is the ratio of output SNR^2 and input SNR^2 as seen by the imaging system. If the imaging system is processing signal and noise correctly, the system should show more output signal and relatively less noise for 29KV than 27KV. Consequently, DQE should be better for a 29KV exposure than for 27KV. I think if you rewatch the video and read the text under figure 4-37 that may also help to understand. This part of my answer will apply if you have two different mammography machines, and you are comparing DQE of different image receptor systems on these machines. In this case you need to calculate the MTFs and NPS for both systems. Also check the beam spectrum, beam quality and output to make sure they are comparable and determine what corrections need to be made if they are not comparable. Once you do these things you can try to compare the DQEs for the imaging systems at the two KVs. Sorry for the long answer but I hope it gives you some insight if it does not fully answer your question.

no problem.

You're welcome!

​@physicsforradiologyresiden4141

P0

​

000😊0😊

Hello Blake, sorry for the late response. Mammo tubes are usually made of Mo or Rh targets with different filter combinations (Mo/Mo, Mo/Rh). For DBT systems, Rhodium and Tungsten (W) target will also be an option for the tube. With Rhodium and Tungsten, the filters used are Rh, Ag, or Al. Different vendors may have proprietary features (like different filter thickness) and optimized spectra but in general the tube targets and filter combinations are as stated above. Hope this answers your question.

Hello Saadiq, sorry for the late response. Did you mean you want a pdf?