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Low dose X-ray CT image reconstruction method based on completely generalized variational regularization

A CT image, low-dose technology, applied in the field of medical imaging, can solve problems such as loss of efficacy, block artifacts, and image ladder effects

Inactive Publication Date: 2016-08-10
GANNAN NORMAL UNIV
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Problems solved by technology

However, many clinical CT images do not fully satisfy the assumption of segmentation constant. When the dose is extremely low or the projection angle is extremely small, the TV reconstructed image will produce staircase effects and blocky artifacts
Therefore, TV regularization will lose its due effect in low-dose CT reconstruction based on projection data restoration

Method used

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  • Low dose X-ray CT image reconstruction method based on completely generalized variational regularization
  • Low dose X-ray CT image reconstruction method based on completely generalized variational regularization
  • Low dose X-ray CT image reconstruction method based on completely generalized variational regularization

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Embodiment 1

[0053] A low-dose X-ray CT image reconstruction method based on full generalized variational regularization is provided, which is carried out through the following steps.

[0054] (1) Obtain the system parameters of the CT equipment and the projection data q after logarithmic transformation under the low-dose scanning protocol. The acquired system parameters of the CT equipment include X-ray incident photon intensity I 0 Wait.

[0055] (2) Anscombe transformation is performed on the projection data q obtained in step (1), and the projection data q subject to the composite Poission distribution is transformed into the Gaussian distribution data u approximately subject to a variance of 1.

[0056] Perform Anscombe transformation on the projection data q obtained in step (1), and the calculation formula is as follows:

[0057]

[0058] u=(u 1 , u 2 ,...,u N ) T Indicates that the projection data approximately obeys the Gaussian distribution data with a variance of 1 afte...

Embodiment 2

[0086] In order to further verify the effect of the present invention, adopt figure 2 The Clock digital phantom image shown and Figure 5 The shown Shepp-Logan digital phantom image is used as the computer simulation experiment object of the present invention.

[0087] (1) The size of the phantom image is set at 512×512, the distances from the X-ray source of the simulated CT machine to the rotation center and the detector are 570mm and 1040mm respectively, and the sampling value of the rotation angle is 1160 between [0,2π]. Each sampling angle corresponds to 672 detector units, and the size of the detector unit is 1.407mm. The projection data q with a size of 1160×672 is generated by CT system simulation. For the Clock phantom, the number of incident photons is 5.0×104; the number of incident photons for the corresponding Shepp-Logan phantom is 2.5×10 5 . It should be noted that, in the actual CT data acquisition, the projection data and system parameters, namely the inci...

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Abstract

The invention provides a low dose X-ray CT image reconstruction method based on completely generalized variational regularization. The method comprises the following steps that (1) the system parameters of CT equipment and projection data after logarithmic transformation under a low dose scanning protocol are acquired; (2) Anscombe transformation is performed on the projection data, and the projection data obeying Poission distribution are converted into Gaussian distribution data u of which approximate obeying variance is 1; (3) an ideal data restoration model based on completely generalized variational minimization is established, and the restored projection data f are obtained through solving by using a Chambolle-Pock algorithm; and (4) inverse Anscombe transformation is performed on the restored projection data f obtained in the step (3), and a CT reconstruction image is obtained through a filtering back projection algorithm. According to the method, noise and bar artifacts of the image can be removed under the premise that the projection data do not meet the piecewise constant hypothesis, and the spatial resolution of the image can be greatly maintained.

Description

technical field [0001] The invention relates to the technical field of medical imaging, in particular to a low-dose X-ray CT image reconstruction method based on full generalized variational regularization. Background technique [0002] X-ray computed tomography (Computed Tomography, CT) has been widely used in clinical diagnosis and treatment because of its excellent performance in time and space resolution. The quality of CT images is closely related to the dose of X-ray radiation. The higher the dose, the better the image quality. However, excessive X-ray exposure can induce malignant tumors, leukemia and other genetic diseases. [0003] In order to reduce the radiation dose of X-rays, many optimized low-dose CT scanning schemes and reconstruction algorithms to suppress noise and artifacts have been proposed one after another. At present, directly reducing the tube current, tube voltage or reducing the number of scan angular samples is the simplest and most effective way...

Claims

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Application Information

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IPC IPC(8): G06T11/00
CPCG06T11/005G06T11/008G06T2211/40
Inventor 牛善洲李楠吴恒马建华喻高航
Owner GANNAN NORMAL UNIV
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