Limits...
A method of extending the depth of focus of the high-resolution X-ray imaging system employing optical lens and scintillator: a phantom study.

Li G, Luo S, Yan Y, Gu N - Biomed Eng Online (2015)

Bottom Line: Based on this advantage, it can effectively image tissues, cells and many other small samples, especially the calcification in the vascular or in the glomerulus.Based on the algorithm proposed, we recovered the blur image and the result in the experiment showed that the proposed algorithm has good performance on the recovery of image blur caused by unmatching thickness of scintillator.But, the quality of the recovery image especially of the low contrast image depends on the noise level of the degraded blur image, so there is room for improving and the corresponding denoising algorithm is worthy for further study and discussion.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: The high-resolution X-ray imaging system employing synchrotron radiation source, thin scintillator, optical lens and advanced CCD camera can achieve a resolution in the range of tens of nanometers to sub-micrometer. Based on this advantage, it can effectively image tissues, cells and many other small samples, especially the calcification in the vascular or in the glomerulus. In general, the thickness of the scintillator should be several micrometers or even within nanometers because it has a big relationship with the resolution. However, it is difficult to make the scintillator so thin, and additionally thin scintillator may greatly reduce the efficiency of collecting photons.

Methods: In this paper, we propose an approach to extend the depth of focus (DOF) to solve these problems. We develop equation sets by deducing the relationship between the high-resolution image generated by the scintillator and the degraded blur image due to defect of focus first, and then we adopt projection onto convex sets (POCS) and total variation algorithm to get the solution of the equation sets and to recover the blur image.

Results: By using a 20 μm thick unmatching scintillator to replace the 1 μm thick matching one, we simulated a high-resolution X-ray imaging system and got a degraded blur image. Based on the algorithm proposed, we recovered the blur image and the result in the experiment showed that the proposed algorithm has good performance on the recovery of image blur caused by unmatching thickness of scintillator.

Conclusions: The method proposed is testified to be able to efficiently recover the degraded image due to defect of focus. But, the quality of the recovery image especially of the low contrast image depends on the noise level of the degraded blur image, so there is room for improving and the corresponding denoising algorithm is worthy for further study and discussion.

Show MeSH

Related in: MedlinePlus

Quantitative quality evaluation of the recovery image for different levels of Poisson noise: (a) recovery image when incident photons number is 2.5 × 106, (b) local SNR in the region encompassed by the square of (a) for different levels of noise, (c) PSNR for different levels of noise.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4306104&req=5

Figure 7: Quantitative quality evaluation of the recovery image for different levels of Poisson noise: (a) recovery image when incident photons number is 2.5 × 106, (b) local SNR in the region encompassed by the square of (a) for different levels of noise, (c) PSNR for different levels of noise.

Mentions: Here, MSE represents the Mean Square Error between the true image and the recovery image. In the experiment, several different levels of Poisson noise were added to the noise-free degraded blur image. From the recovery image in Figure 7(a) we can see that when the incident photon number reaches to 2.5 × 106, the corresponding Poisson noise has nearly no impact against the quality of the recovery image. And from the local SNR and global PSNR curves for different noise level shown in Figure 7(b) (c), we can quantitatively determine how the noise level impacts the recovery image quality, so the curves can help us in practice to determine which noise level is suitable according to the quality requirement.


A method of extending the depth of focus of the high-resolution X-ray imaging system employing optical lens and scintillator: a phantom study.

Li G, Luo S, Yan Y, Gu N - Biomed Eng Online (2015)

Quantitative quality evaluation of the recovery image for different levels of Poisson noise: (a) recovery image when incident photons number is 2.5 × 106, (b) local SNR in the region encompassed by the square of (a) for different levels of noise, (c) PSNR for different levels of noise.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4306104&req=5

Figure 7: Quantitative quality evaluation of the recovery image for different levels of Poisson noise: (a) recovery image when incident photons number is 2.5 × 106, (b) local SNR in the region encompassed by the square of (a) for different levels of noise, (c) PSNR for different levels of noise.
Mentions: Here, MSE represents the Mean Square Error between the true image and the recovery image. In the experiment, several different levels of Poisson noise were added to the noise-free degraded blur image. From the recovery image in Figure 7(a) we can see that when the incident photon number reaches to 2.5 × 106, the corresponding Poisson noise has nearly no impact against the quality of the recovery image. And from the local SNR and global PSNR curves for different noise level shown in Figure 7(b) (c), we can quantitatively determine how the noise level impacts the recovery image quality, so the curves can help us in practice to determine which noise level is suitable according to the quality requirement.

Bottom Line: Based on this advantage, it can effectively image tissues, cells and many other small samples, especially the calcification in the vascular or in the glomerulus.Based on the algorithm proposed, we recovered the blur image and the result in the experiment showed that the proposed algorithm has good performance on the recovery of image blur caused by unmatching thickness of scintillator.But, the quality of the recovery image especially of the low contrast image depends on the noise level of the degraded blur image, so there is room for improving and the corresponding denoising algorithm is worthy for further study and discussion.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: The high-resolution X-ray imaging system employing synchrotron radiation source, thin scintillator, optical lens and advanced CCD camera can achieve a resolution in the range of tens of nanometers to sub-micrometer. Based on this advantage, it can effectively image tissues, cells and many other small samples, especially the calcification in the vascular or in the glomerulus. In general, the thickness of the scintillator should be several micrometers or even within nanometers because it has a big relationship with the resolution. However, it is difficult to make the scintillator so thin, and additionally thin scintillator may greatly reduce the efficiency of collecting photons.

Methods: In this paper, we propose an approach to extend the depth of focus (DOF) to solve these problems. We develop equation sets by deducing the relationship between the high-resolution image generated by the scintillator and the degraded blur image due to defect of focus first, and then we adopt projection onto convex sets (POCS) and total variation algorithm to get the solution of the equation sets and to recover the blur image.

Results: By using a 20 μm thick unmatching scintillator to replace the 1 μm thick matching one, we simulated a high-resolution X-ray imaging system and got a degraded blur image. Based on the algorithm proposed, we recovered the blur image and the result in the experiment showed that the proposed algorithm has good performance on the recovery of image blur caused by unmatching thickness of scintillator.

Conclusions: The method proposed is testified to be able to efficiently recover the degraded image due to defect of focus. But, the quality of the recovery image especially of the low contrast image depends on the noise level of the degraded blur image, so there is room for improving and the corresponding denoising algorithm is worthy for further study and discussion.

Show MeSH
Related in: MedlinePlus