X-ray CT scan end position determination using bone ratio threshold
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Solution Overview
Problem
Existing X-ray CT apparatuses face challenges in accurately determining the scan end position during scanning, leading to potential shifts and reduced accuracy due to radiation hardening and unclear images of deeper body parts.
Innovation Solution
An X-ray CT apparatus with a rotating plate, bed, image generator, storage unit, region extraction unit, and comparison determination unit that calculates and compares region ratios from tomographic images to determine the scan end position based on pre-determined threshold values, ensuring accurate termination of scanning without excess or deficiency in measurement range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If projection data comparison is used to determine scan end position, then scan termination can be automated, but accuracy deteriorates due to radiation hardening causing unclear images of deeper body parts
Solution Approach 1:
The patent changes the parameter basis for determination from projection data (which suffers from radiation hardening) to bone ratio in tomographic images. By extracting bone regions and calculating their ratio in sequential tomographic images, the system determines scan end position based on bone ratio changes rather than projection data intensity, thereby avoiding the radiation hardening problem while maintaining automated operation.
2Reliability
If scanning continues beyond necessary position, then complete coverage is ensured, but exposure time and radiation dose increase
Solution Approach 1:
The patent replaces the mechanical/physical approach of continuous scanning with a computational image analysis approach. By using region extraction to identify bone regions and calculating bone ratios in tomographic images, the system can precisely determine when the scan should terminate based on anatomical landmarks, avoiding unnecessary scanning while ensuring complete coverage of required areas.
3Area of stationary object
If projection data from deeper regions is used for comparison, then full anatomical coverage is assessed, but image quality degrades due to radiation hardening
Solution Approach 1:
The patent extracts bone regions from tomographic images using region extraction technology. By isolating and analyzing only the bone regions rather than using entire projection data or full anatomical images, the system obtains clear, high-contrast data for determination purposes. This extraction approach eliminates the degradation caused by radiation hardening in deeper soft tissue regions while still assessing complete anatomical coverage through bone landmark identification.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables more accurate determination of the scan end position, preventing degradation in accuracy and reducing unnecessary exposure and scan time by ensuring precise measurement ranges, even for deeper body parts.
Implementation Method 1
an X-ray source to emit an X-ray to a subject and an X-ray detector, oppositely provided to the X-ray source, to detect the X-ray transmitted through the subject
Implementation Method 2
a rotating plate that rotates an X-ray source to emit an X-ray to a subject and an X-ray detector, oppositely provided to the X-ray source, to detect the X-ray transmitted through the subject, around the subject
Implementation Method 3
An X-ray CT apparatus is a device to generate a tomographic image of a subject by measuring projection data as an X-ray projection image of the subject at various projection angles, and performing reconstruction calculation on the multiple projection data
Data Source
AI summary
An X-ray CT apparatus enables accurate determination of a scan end position and includes a rotating plate that rotates an X-ray source and an X-ray detector, oppositely provided to the X-ray source, to detect the X-ray transmitted through and around the subject. A bed for the subject moves with respect to the rotating plate, to change a scan position; and a tomographic image is generated in the scan position based on output from the X-ray detector. A storage holds a region ratio threshold value previously determined in a scan end position. A region extraction unit extracts a predetermined region from the tomographic image generated during scanning; and a comparison determination unit determines whether or not the scan position has arrived at the scan end position based on comparison between a region ratio calculated by using the region and the threshold value.