CT Back Projection Redundant Data Arrangement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current CT image reconstruction methods are slow due to extensive real-number calculations and inefficient data processing in the back projection step, particularly in the innermost loop of the triple loop calculation.
Innovation Solution
The method involves rearranging projection data into a redundant arrangement form to facilitate efficient memory access and performing vector operations, allowing for simultaneous calculations and reducing real-number arithmetic operations, thereby speeding up the back projection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional back projection calculation is performed with standard data arrangement, then calculation accuracy is maintained, but processing speed is slow due to extensive real-number calculations and inefficient memory access
Solution Approach 1:
The patent applies preliminary action by pre-arranging projection data into a redundant arrangement form before the back projection calculation begins. This preprocessing step organizes data in memory to match the calculation pattern, so that during the actual back projection process, no additional real-number calculations are needed for data access and alignment. The redundant arrangement stores multiple copies of projection data at different memory locations, allowing direct retrieval during calculation without time-consuming address computations.
Solution Approach 2:
The patent segments the calculation process by separating the data arrangement phase from the calculation phase. The projection data is divided and arranged in specific redundant patterns in memory, which allows the back projection calculation to proceed with simple data retrieval and addition operations rather than complex real-number calculations. This segmentation enables the calculation to be performed more efficiently by eliminating computational overhead during the critical calculation loop.
2Productivity
If standard data access methods are used in back projection, then memory access is simple, but processing efficiency is low due to frequent real-number arithmetic operations
Solution Approach 1:
The patent changes the parameter of data arrangement from standard sequential storage to a redundant arrangement form. In this new arrangement, projection data is stored multiple times at different memory locations corresponding to the angles and positions needed for back projection. This parameter change transforms the calculation from requiring complex real-number arithmetic for data transformation to simple memory retrieval and addition operations, significantly improving calculation efficiency.
3Measurement precision
If real-number interpolation calculations are performed in the innermost loop, then calculation precision is maintained, but processing speed decreases due to the large number of arithmetic operations
Solution Approach 1:
The patent performs the interpolation arrangement in advance during the data preparation phase, creating a redundant data structure that encodes the interpolated values directly in memory. This eliminates the need for real-number interpolation calculations during the innermost loop execution. The redundant arrangement pre-computes and stores the necessary data relationships, allowing the inner loop to execute with only simple memory access and addition operations, thereby maintaining precision while dramatically improving speed.
Data Source
AI summary
A back projection method in CT image reconstruction method in which projection data obtained by irradiating a subject with electromagnetic wave and detecting the electromagnetic wave transmitted through the subject are back-projected onto a CT image reconstruction region virtually set on a region of interest of the subject, said back projection method comprising: generating a projected image redundant arrangement form in which the projection data are arranged so as to be redundant and gathered to access units; and performing a vector operation for the projection data arranged in the projected image redundant arrangement form. According to the back projection method of the invention, the vector operation can be performed efficiently while real-number arithmetic operation which is necessary for addressing can be omitted. Accordingly, back projection calculation can be performed speedily.