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ASTM E2737 Five Groove Wedge https://www.x-ray-forum.net/./22161106nx65772/iqi-image-quality-indicator-f91/astm-e2737-five-groove-wedge-t42.html |
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Author: | JanT [ 13.12.2019, 08:42 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
Some example of the material effect that Klaus mentioned: This image was taken with the steel version of the wedge and an Yxlon minifocus tube with 160kV at 6.5mA and a 0.5mm Cu filter. The detector is a Varex 4343 DXi with DRZ+ scintillator and 60 seconds integration time at 1x1 resolution with 4pF. Even with the great image enhancement, the center line is difficult to trace. |
Author: | Colin Gan [ 09.08.2021, 09:40 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
I have a question about five groove wedge. As we realize that the "five groove" is using for IQI parameters test, there is another structures on the plane of five groove, however I couldn't find any description about using these structures for IQI testing. So What are these structures designed to do ? |
Author: | Klaus [ 09.08.2021, 12:53 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
Colin, as far as I know the five groove wedge is intended only for usage in Digital Detector Array Performance Evaluation and Long-Term Stability Tests which are descriped in ASTM E2737. What do you mean with "IQI-Testing"? And what kind of structures do you mean? |
Author: | Colin Gan [ 10.08.2021, 06:29 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
Klaus wrote: Colin, as far as I know the five groove wedge is intended only for usage in Digital Detector Array Performance Evaluation and Long-Term Stability Tests which are descriped in ASTM E2737. What do you mean with "IQI-Testing"? And what kind of structures do you mean? sorry, my mistake, I mean DDA performance evaluation and long-term stability test. second ,see the image(from E2737 FIG. X1.2). |
Author: | Klaus [ 10.08.2021, 08:30 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
Sorry, that ist funny This marks are indicators that should help you to see where you are with the line profile if you are moving the line from the thinnest thickness to the larger thickness (see 9.3.1.2 and FIG. 3 Moving the Line Profile on the Wedge from Thin to Thicker Material in E2737, page 9). The usage of the 5 groove wedge is to see, where the line you are looking for disappears in the noise. Then you should look at the indication on the side and by the marks you could see it in [mm] or ["]. The [mm] indicator come with single and double dots - this should help the reading. |
Author: | Colin Gan [ 30.08.2021, 15:11 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
thanks. I have two more quetions: 1. In 9.3.4, the SNR is measured in area with changing thickness(Fig.4), thus the noise is "the median single line standard deviation", the question is that the noise value is difficult to measure by using software, is there other way to measure it? 2.In 8.2.5.3,it mentioned that “a sequence of images shall then be captured for about 20s while shutting down the X-rays after approximately three seconds” , and in 9.5.1, it says "A ROI of about 50 by 10 pixels shall be drawn in the area where the signal level is about 85% of the signal level in image L Img 1 for the same ROI......The next image in the sequence [L Img S1] shall be taken and the same ROI shall be drawn at the same position in that image(9.5.1.2)". Well, for our DDA system , we can barely capture images that " the signal level is about 85% of the signal level in image L Img 1" , even capture images immediately while shutting down the X-rays instead of "after approximately three seconds (8.2.5.3)", the gray value is too low and far from that, therefore the image lag can not be measured successfully. I really have no idea who to ask for help...... |
Author: | Klaus [ 30.08.2021, 17:25 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
Colin Gan wrote: Actually I have another question about E2737. In 9.3.4 Signal to Noise Ratio, it says that SNR is the quotient of the mean gray value and the median single line standard deviation(noise), and in FIG. 4 Measure the Mean Grey Value(Signal Level) and Median Single Line Standard Deviation(Sigma), there is an ROI size of 67*48, I have some confusion about understanding the notion of "median single line", does that mean that the line is IN the middle of the ROI(i.e. , in this case, the 24th line, or the 25th line, or the mean gray of them)? It seems that , in E2737, the software for measuring the images is Isee, however I was told that, in the version of 2019, the function about measuring "median single line mean" has been removed, in fact, I haven't seen the same function in other DR image measuring software. it confus me for a while...... The median single line sigma is the sigma of the line, which sigma value is the median sigma value of all lines. It is similar to a median filter in image processing. The procedure is first described in ASTM E2446-16_Practice_for_Classification_of_Computed_Radiology_Systems in 6.1.1.8. There is another image measuring software, which has this function build in: Image 3500 from YXLON. And - as far as I know - also the GE and Visiconsult Softwares should be able to do this function. Which Softwares did you look for and missed it? |
Author: | Klaus [ 30.08.2021, 17:36 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
Colin Gan wrote: thanks. I have two more quetions: 1. In 9.3.4, the SNR is measured in area with changing thickness(Fig.4), thus the noise is "the median single line standard deviation", the question is that the noise value is difficult to measure by using software, is there other way to measure it? 2.In 8.2.5.3,it mentioned that “a sequence of images shall then be captured for about 20s while shutting down the X-rays after approximately three seconds” , and in 9.5.1, it says "A ROI of about 50 by 10 pixels shall be drawn in the area where the signal level is about 85% of the signal level in image L Img 1 for the same ROI......The next image in the sequence [L Img S1] shall be taken and the same ROI shall be drawn at the same position in that image(9.5.1.2)". Well, for our DDA system , we can barely capture images that " the signal level is about 85% of the signal level in image L Img 1" , even capture images immediately while shutting down the X-rays instead of "after approximately three seconds (8.2.5.3)", the gray value is too low and far from that, therefore the image lag can not be measured successfully. I really have no idea who to ask for help...... 1. As far as I know the noise could only be measured by software as it is a mathematical function. Here the median line value is required as you have a gradient on the columns which will spoil the SNR value. 2. Normally a detector will be read out sequencly - the first pixel is read out just after the very last pixel - as the DDAs normally have no shutter. When you shut down the tube there will be an image where the brightness is reduce a bit - mainly in a part of the image. If you capture a sequence of images you will have one image with this condition. Take this image as start image for measurement and there the area where the signal is dropped to about 85%. Actually E2737 is back from sub-ballot and in the version in ballot the lag measurement is removed from this standard. It will stay in E2597 only. If E2737 also passes the main ballot it will have no lag measurement anymore ... |
Author: | Klaus [ 30.08.2021, 17:42 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
Colin Gan wrote: (somehow it shows submit successfully, but actually failed, so I have to retype again ) The forum software seems to see you post as SPAM, because your post needed to be approved for some reasons (which I do not know ). Sorry for this |
Author: | Colin Gan [ 31.08.2021, 14:40 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
Quote: Which Softwares did you look for and missed it? We are now using ISee! Professional 2017 (we are asking update....for CNR measuring). The software can just give us a mean gray value for a given ROI, and seems unable to give the "median sigma value of all lines". Our manufacturer supplied us with another software, which could not do it either.... Quote: If you capture a sequence of images you will have one image with this condition Tell me if I am wrong, in the process of image-lag measurement, we set the capture speed of 1frame/s, thus one image per second, during the 20s after shutting down the X-ray, we have a number of images. However, the gray value seems to drop too fast to be about 85%, in fact, we can barely see the lag in the first image. The same question occurred in measuring Burn-in, according to 9.5.2, we measured the Burn-in (BI img 1)=0.37%, but we can hardly see the phantom in BI Img10. So, is it possible that gray value drop too fast result in unsatisfied image? or we did it wrong? |
Author: | Klaus [ 02.09.2021, 10:07 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
The ISee Software is used to do the tests for the CR qualification (ASTM E2446) - therefore I am quite sure you could also do the median line SNR. Uwe Zscherpel guided the design of this software, you could send a PN to him and ask your question directly "at the source". The lag measurement asumes that you are using the highest frame rate of the detector. Then you will see the 85% of the signal. If the readout time of the detector is small compared to [exposure time - readout time] you may have difficulties to get the frame with the 85%, because the drop down of the intensity of the tube will probably be in a time where you do not read out the detector. The Burn In test makes only sense if you are using a scintillator which is sensitive to burn in (like CsI). If you are using GADOX you will not see a burn in. Please refer to ASTM E2736 for details about the scintillator. |
Author: | Colin Gan [ 05.05.2022, 09:05 ] |
Post subject: | Re: ASTM E2737 Five Groove Wedge |
Hi Klaus: Why do you design the finest grooves as 0.127mm instead of,like 0.1mm |
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