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X-ray CT device and processing device

A technology of X-ray and CT images, applied in the field of iterative reconstruction technology, can solve problems such as increased calculation amount and optimization of a large number of parameters

Active Publication Date: 2016-12-14
HITACHI HEALTHCARE MFG LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, compared with the existing analytical method for calculating CT values, the iterative reconstruction method has problems such as an increase in the amount of calculation caused by repeated updates and optimization of a large number of parameters.

Method used

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  • X-ray CT device and processing device
  • X-ray CT device and processing device
  • X-ray CT device and processing device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] figure 1 A diagram showing a hardware configuration of an X-ray CT apparatus according to Embodiment 1, figure 2 A functional block diagram showing the functions of the X-ray CT apparatus of the first embodiment is shown. This embodiment is an embodiment of such an X-ray CT apparatus, which includes: an imaging unit 102, which includes an X-ray generating unit 1 that generates X-rays, and a unit that detects X-rays transmitted from an object to obtain measurement projection data. The X-ray detection unit 2, and a mechanism that is equipped with the X-ray generation unit and the X-ray detection unit and rotates around the subject; and the image generation unit 103 includes an iterative approximation reconstruction unit 136 based on The CT image is generated from the measured projection data from the imaging unit, and the CT image is iteratively corrected so that the difference between the calculated projection data and the measured projection data obtained by forward p...

Embodiment 2

[0152] Next, the X-ray CT apparatus of Example 2 will be described.

[0153] In the first embodiment described above, in the case where the weight set to a fixed value in the weight setting area 144 is adopted, the reference parameter β b , base weight W b And the weight image W of each position I (j) Calculation parameter β image β I (j) Structure. On the other hand, in Example 2, when the weight setting area 144 is set to the number of photons of the detection element, the reference parameter β calculated with a weight of a fixed value is used. b and base weight W b , and the weight image W of each position calculated by the number of photons of the detection element I (j), to calculate the parameter β image β I (j). The configuration of the X-ray CT apparatus according to the second embodiment will be described below focusing on configurations different from those of the X-ray CT apparatus according to the first embodiment.

[0154] Figure 11 Shown is a weighted i...

Embodiment 3

[0160] Next, the X-ray CT apparatus of Example 3 will be described. In the above-mentioned first embodiment, when the weight set to a fixed value in the weight setting area 144 is used, the reference weight W set at the rotation center at the reference position is used. b , benchmark parameter β b And the weight image W of each position I (j) to calculate the parameter β image β I (j) Structure. In Embodiment 3, not only the center of rotation but a plurality of reference weights W are used b , multiple reference parameters β b And the weight image W of each position I (j), to calculate the parameter β image β I (j) Structure. The configuration of the X-ray CT apparatus according to the third embodiment will be described below focusing on configurations different from those of the X-ray CT apparatus according to the first embodiment.

[0161] Figure 14 The left side of shows that in the table calculation unit 170, when using each reference parameter β bIn the CT ima...

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Abstract

This X-ray CT device uses iterative reconstruction to obtain a CT image with the desired noise reduction or X-ray reduction ratio. An iterative approximation reconstruction unit (136) is provided which, from measured projection data obtained by an X-ray detection unit of the X-ray CT device, iteratively reconstructs a CT image in a reconstruction range of a subject, and iteratively corrects the CT image such that calculated projection data, calculated through forward projection of a CT image, is the same as the difference between measured projection data detected by the X-raw detection unit and calculated projection data. The iterative approximation reconstruction unit is provided with a parameter determination unit (151), an iterative correction unit (152), and a table unit (153) which calculates in advance the relation between each parameter used in the iterative reconstruction, and noise reduction or X-ray reduction ratio in the CT image. The parameter determination unit (151) determines the parameters from a calculation table in the table unit (153) depending on the desired reduction ratio.

Description

technical field [0001] The present invention relates to an X-ray CT (Computed Tomography, computerized tomography) device, in particular to an iterative reconstruction technique for iteratively correcting a CT image. Background technique [0002] An X-ray CT apparatus is a device that calculates the X-ray absorption coefficient at each point in the subject based on the measurement projection data obtained by photographing the subject from multiple directions, and obtains an X-ray absorption coefficient distribution image (hereinafter referred to as CT images). Usually, the X-ray absorption coefficient is replaced by the CT value normalized by air and water (-1000 for air, 0 for water) and used for diagnosis. [0003] A CT image appears as tomographic planes overlapping in the body axis direction of the subject. In medical practice, the use of CT images is clinically useful because it enables accurate and instant diagnosis of a patient's condition. However, under the condi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61B6/03
CPCA61B6/5258A61B6/032A61B6/461A61B6/467A61B6/5205G06T11/006G06T2211/424
Inventor 山川惠介小嶋进一
Owner HITACHI HEALTHCARE MFG LTD
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