ZitatWhich 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....
ZitatIf 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?
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.
I just startet my ISee version and I found the way to get what you are looking for: A) select the statistic box (5) B) in the lower area you will find the median single line mean value and the median single line standard deviation (this is the median sigma value of all lines in the box): and in the next line the quotient of both - the median single line SNR.
Colin, the reason was in the beginning (2004) that the sizes should fit to the Hole Type IQIs of E1025 and it says "1.3 The values stated in inch-pound units are to be regarded as standard."
As it is nearly impossible to manufacture such small grooves (for reasonable costs) we decided to change the groove sizes to (as written in my post from 16.11.2019, 02:16) and now we meet the metric world of ISO standards.
Dear Klaus: When measuring MTR by using five-groove wedge phantom, how should I accurately determine that if the groove "disappeares in the noise" (9.3.1.2)? For now, I rely just on profiler analysis, but measurement results of the same picture were not consistent (a few millimeters of error).
The intention with the grooves is similar to the wire from the Wire Sets (ASTM or EN/ISO) and the five groove wedge was made for users who do not want to use too much technique when doing the evaluation. With the wire you say: "I see it" or "I don't see it" and here the visual interpretation was in our minds when we created this IQI. A deviation of a few millimeters should not be an issue as noise is mainly the limit ...
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ASTM E2737 Five Groove Wedge
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Mon Aug 30, 2021 6:42 pm
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