X-ray CT Apparatus Cache Hit Ratio Optimization
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Solution Overview
Problem
The existing X-ray CT image processing methods suffer from reduced cache hit ratios during reverse projection, leading to delays in image processing due to unnecessary data being moved between main and cache memory.
Innovation Solution
An X-ray CT apparatus is designed with a processor that rearranges projection data and generates corresponding view weights, storing only necessary data in the cache memory for reverse projection processing, thereby improving cache hit ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous projection data is transferred from main memory to cache memory for reverse projection, then the reverse projection processing can be performed, but the cache hit ratio is reduced because data not used in reverse projection is also moved to cache memory
Solution Approach 1:
The projection data is divided into multiple segments based on view ranges. Only the necessary segments corresponding to the required views are transferred to cache memory, while other segments remain in main memory. This segmentation allows selective data transfer, improving cache hit ratio by ensuring that only frequently accessed projection data resides in cache memory.
Solution Approach 2:
The necessary projection data segments are pre-transferred from main memory to cache memory before reverse projection processing begins. This preliminary action ensures that the required data is already in cache memory when needed, maximizing cache hit ratio and avoiding repeated main memory accesses during processing.
2Speed
If all continuous projection data is moved to cache memory, then reverse projection can proceed without main memory access delays, but unnecessary data occupies cache memory space reducing the cache hit ratio
Solution Approach 1:
Only the necessary projection data segments required for reverse projection are extracted and transferred to cache memory, while unnecessary data remains in main memory. This extraction principle ensures that cache memory space is utilized efficiently for only the data that will be accessed, maintaining high data access speed while avoiding the penalty of moving unnecessary data.
3Reliability
If projection data is selectively arranged by view ranges, then only necessary data is stored in cache memory improving cache hit ratio, but additional data rearrangement processing is required
Solution Approach 1:
Projection data is segmented according to view ranges, with each segment containing data for a specific angular range. This segmentation structure simplifies the selection process during reverse projection, as data can be directly accessed by view range without complex search or filtering operations, thereby reducing overall system complexity despite the initial arrangement step.
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 enhances the cache hit ratio during reverse projection, reducing processing delays and improving the efficiency of image reconstruction in X-ray CT systems.
Implementation Method 1
an X-ray tube (107); an X-ray detector (108), oppositely provided to the X-ray tube, that detects an X-ray generated with the X-ray tube and transmitted through a subject
Data Source
AI summary
When image reconstruction by retrospective scanning is performed, the cache hit ratio is lowered due to transfer of not-used projection data to a cache memory. Accordingly, a processor generates rearranged projection data in which a first plurality of segments are extracted from original projection data written in a memory for saving original projection data 205, and stores the generated rearranged projection data into a main memory 212. The processor generates second view weights in which first view weights are made to correspond with the rearranged projection data (209). The rearranged projection data stored in the main memory 212 is previously transferred to the cache memory 213. The processor generates first tomographic image data with the rearranged projection data and the second view weights (214).