In the diagnostic images, the Noise Power Spectrum(NPS) of radiography system has been used for evaluating noise characteristic, especially for granuality with method of RMS(Root Mean Square) graunality.
In this study, radiographic images were obtained according to four RQA conditions(3, 5, 7, a...
In the diagnostic images, the Noise Power Spectrum(NPS) of radiography system has been used for evaluating noise characteristic, especially for granuality with method of RMS(Root Mean Square) graunality.
In this study, radiographic images were obtained according to four RQA conditions(3, 5, 7, and 9), and NPS was obtained from each image by referring to the method described in IEC 62220-1. From the obtained NPS data, the energy dependence of the NPS of the image according to the X-ray spectrum change was measured.
I investigated the effect of X-ray spectrum change on NPS, which is a noise characteristic of detector, and verified the difference of NPS according to radiation quality. In addition, I made a phantom that can be used for visual evaluation with materials that can be easily found in the vicinity of rice and beans, so that it was possible to evaluate noise such as SNR as well as conventional phantom by a simple experiment.
As a result of NPS (Normalized NPS) calculation, NPS tended to increase with increasing energy. A high NPS means that there is a relatively large amount of noise in the image. In the visual evaluation, it was confirmed that the noise increased as the energy increased, and the same result with NPS could be obtained. It can be evaluated not only by the expensive Radiographic QA Phantom, but also by the simplified phantom made of rice and beans, which can be easily obtained from the surroundings. In addition, the NPS obtained from each RQA condition did not show any significant difference in numerical value, but it was confirmed that the difference was apparent in the visual evaluation.
In medical imaging, the value or contrast of the signal to be detected is not necessarily large. Even if the whole image is clearly visible, it can be a useful image if it can not be read if the part to be read is not good, and if the image is not good in appearance, the lesion can be detected.
From the experimental results, it was found that it is important to select the correct X-ray line quality for each test and detector characteristics.
It was confirmed that the noise increases as the X-ray energy becomes higher on the basis of the experiment, in terms of quantitative and qualitative evaluation, respectively. We hope that the results of this study will be useful for the measurement of noise characteristics in the future, and it will be necessary to study the noise characteristics according to the changes of the X-ray spectrum for the detectors made of other materials than those used in this experiment.
In the diagnostic images, the Noise Power Spectrum(NPS) of radiography system has been used for evaluating noise characteristic, especially for granuality with method of RMS(Root Mean Square) graunality.
In this study, radiographic images were obtained according to four RQA conditions(3, 5, 7, and 9), and NPS was obtained from each image by referring to the method described in IEC 62220-1. From the obtained NPS data, the energy dependence of the NPS of the image according to the X-ray spectrum change was measured.
I investigated the effect of X-ray spectrum change on NPS, which is a noise characteristic of detector, and verified the difference of NPS according to radiation quality. In addition, I made a phantom that can be used for visual evaluation with materials that can be easily found in the vicinity of rice and beans, so that it was possible to evaluate noise such as SNR as well as conventional phantom by a simple experiment.
As a result of NPS (Normalized NPS) calculation, NPS tended to increase with increasing energy. A high NPS means that there is a relatively large amount of noise in the image. In the visual evaluation, it was confirmed that the noise increased as the energy increased, and the same result with NPS could be obtained. It can be evaluated not only by the expensive Radiographic QA Phantom, but also by the simplified phantom made of rice and beans, which can be easily obtained from the surroundings. In addition, the NPS obtained from each RQA condition did not show any significant difference in numerical value, but it was confirmed that the difference was apparent in the visual evaluation.
In medical imaging, the value or contrast of the signal to be detected is not necessarily large. Even if the whole image is clearly visible, it can be a useful image if it can not be read if the part to be read is not good, and if the image is not good in appearance, the lesion can be detected.
From the experimental results, it was found that it is important to select the correct X-ray line quality for each test and detector characteristics.
It was confirmed that the noise increases as the X-ray energy becomes higher on the basis of the experiment, in terms of quantitative and qualitative evaluation, respectively. We hope that the results of this study will be useful for the measurement of noise characteristics in the future, and it will be necessary to study the noise characteristics according to the changes of the X-ray spectrum for the detectors made of other materials than those used in this experiment.
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