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Removing Noises Induced by Gamma Radiation in Cerenkov Luminescence Imaging Using a Temporal Median Filter

View Article: PubMed Central - PubMed

ABSTRACT

Cerenkov luminescence imaging (CLI) can provide information of medical radionuclides used in nuclear imaging based on Cerenkov radiation, which makes it possible for optical means to image clinical radionuclide labeled probes. However, the exceptionally weak Cerenkov luminescence (CL) from Cerenkov radiation is susceptible to lots of impulse noises introduced by high energy gamma rays generating from the decays of radionuclides. In this work, a temporal median filter is proposed to remove this kind of impulse noises. Unlike traditional CLI collecting a single CL image with long exposure time and smoothing it using median filter, the proposed method captures a temporal sequence of CL images with shorter exposure time and employs a temporal median filter to smooth a temporal sequence of pixels. Results of in vivo experiments demonstrated that the proposed temporal median method can effectively remove random pulse noises induced by gamma radiation and achieve a robust CLI image.

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Related in: MedlinePlus

The traditional denoising method for CLI. (a) Original CLI image captured with 60 s exposure time. (b–d) Filtered CLI images using median filter with filter window size = 5, 10, and 15. A large filter window size achieves a smooth CLI image with less impulse noises. (e, f) Quantitative analysis of the relations between signal values in region of interest (ROI) marked with red circle and region of background (ROB) marked with red rectangle. The signal values in both ROI and ROB decrease with the increase of filter window size.
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fig5: The traditional denoising method for CLI. (a) Original CLI image captured with 60 s exposure time. (b–d) Filtered CLI images using median filter with filter window size = 5, 10, and 15. A large filter window size achieves a smooth CLI image with less impulse noises. (e, f) Quantitative analysis of the relations between signal values in region of interest (ROI) marked with red circle and region of background (ROB) marked with red rectangle. The signal values in both ROI and ROB decrease with the increase of filter window size.

Mentions: CL signals are so weak that a long exposure time is necessary for CLI. During the long exposure process, a great number of gamma rays may reach CCD sensor and produce heavy random impulse noises. Figure 5(a) is an original CLI image captured with 60 s exposure time. Although 18F-FDG locates in region of the pseudotumor (ROI marked with red circle), lots of impulse noises intersperse among other locations in and out of the mouse without 18F-FDG as a result of the reach of gamma rays with arbitrary directions. Figures 5(b)–5(d) are filtered CLI images using median filter with different filter window sizes. The filtered CLI image with small filter window size contains lots of noises but the pixel values in region of signal are close to that of the original CLI image (Figure 5(b)). While a large filter window size can obtain an enough smooth filtered CLI image, the pixel values in region of signal are much smaller than that of the original CLI image (Figure 5(d)). Figures 5(e) and 5(f) are the quantified results of pixel values in ROI marked with red circle and ROB marked with red rectangle in the original CLI image.


Removing Noises Induced by Gamma Radiation in Cerenkov Luminescence Imaging Using a Temporal Median Filter
The traditional denoising method for CLI. (a) Original CLI image captured with 60 s exposure time. (b–d) Filtered CLI images using median filter with filter window size = 5, 10, and 15. A large filter window size achieves a smooth CLI image with less impulse noises. (e, f) Quantitative analysis of the relations between signal values in region of interest (ROI) marked with red circle and region of background (ROB) marked with red rectangle. The signal values in both ROI and ROB decrease with the increase of filter window size.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5015013&req=5

fig5: The traditional denoising method for CLI. (a) Original CLI image captured with 60 s exposure time. (b–d) Filtered CLI images using median filter with filter window size = 5, 10, and 15. A large filter window size achieves a smooth CLI image with less impulse noises. (e, f) Quantitative analysis of the relations between signal values in region of interest (ROI) marked with red circle and region of background (ROB) marked with red rectangle. The signal values in both ROI and ROB decrease with the increase of filter window size.
Mentions: CL signals are so weak that a long exposure time is necessary for CLI. During the long exposure process, a great number of gamma rays may reach CCD sensor and produce heavy random impulse noises. Figure 5(a) is an original CLI image captured with 60 s exposure time. Although 18F-FDG locates in region of the pseudotumor (ROI marked with red circle), lots of impulse noises intersperse among other locations in and out of the mouse without 18F-FDG as a result of the reach of gamma rays with arbitrary directions. Figures 5(b)–5(d) are filtered CLI images using median filter with different filter window sizes. The filtered CLI image with small filter window size contains lots of noises but the pixel values in region of signal are close to that of the original CLI image (Figure 5(b)). While a large filter window size can obtain an enough smooth filtered CLI image, the pixel values in region of signal are much smaller than that of the original CLI image (Figure 5(d)). Figures 5(e) and 5(f) are the quantified results of pixel values in ROI marked with red circle and ROB marked with red rectangle in the original CLI image.

View Article: PubMed Central - PubMed

ABSTRACT

Cerenkov luminescence imaging (CLI) can provide information of medical radionuclides used in nuclear imaging based on Cerenkov radiation, which makes it possible for optical means to image clinical radionuclide labeled probes. However, the exceptionally weak Cerenkov luminescence (CL) from Cerenkov radiation is susceptible to lots of impulse noises introduced by high energy gamma rays generating from the decays of radionuclides. In this work, a temporal median filter is proposed to remove this kind of impulse noises. Unlike traditional CLI collecting a single CL image with long exposure time and smoothing it using median filter, the proposed method captures a temporal sequence of CL images with shorter exposure time and employs a temporal median filter to smooth a temporal sequence of pixels. Results of in vivo experiments demonstrated that the proposed temporal median method can effectively remove random pulse noises induced by gamma radiation and achieve a robust CLI image.

No MeSH data available.


Related in: MedlinePlus