CT Reference Dose Parameter Calculation via Water Equivalent Diameter
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Solution Overview
Problem
Current methods for calculating x-ray dose in computed tomography imaging are inefficient, as they require large data volumes and are not compatible across different CT devices, making it difficult to compare doses independently and accurately, especially in distributed computing environments.
Innovation Solution
A method based on water equivalent diameter (WED) and noise level to determine a reference dose parameter, which is indirectly proportional to the noise level, allowing for rapid calculation without transmitting large data volumes, and is independent of the CT device manufacturer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Monte-Carlo simulation is used to calculate dose parameter based on axial slice images, then measurement precision is improved, but quantity of substance increases and productivity decreases
Solution Approach 1:
The patent extracts only the essential information needed for dose calculation (recording parameters and water equivalent diameter) from the complete axial slice images. By taking out only the necessary data elements rather than processing entire images, the method achieves accurate dose parameter calculation without requiring large data volumes for transmission and storage.
Solution Approach 2:
The patent segments the dose calculation process into two parts: (1) calculating dose parameter from recording parameters using a standardized model applicable to all devices, and (2) determining water equivalent diameter from axial slice images only when needed for patient-specific adjustments. This segmentation allows most calculations to be performed without large image data.
2Measurement precision
If Monte-Carlo simulation is used to calculate dose parameter from axial slice images, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent performs preliminary calculation of dose parameters using recording parameters and standardized models before actual imaging or during planning phase. By pre-calculating dose parameters based on recording parameters alone, the method avoids time-consuming Monte-Carlo simulations during clinical workflow, significantly improving productivity while maintaining accuracy through subsequent water equivalent diameter adjustments when needed.
3Productivity
If dose parameter is calculated based solely on recording parameters, then productivity is improved, but measurement precision and adaptability worsen
Solution Approach 1:
The patent applies local quality by using recording parameters for general dose calculation applicable to all patients and devices, then selectively applying water equivalent diameter derived from axial slice images only for patient-specific dose adjustments. This approach maintains high productivity through standardized calculations while improving precision locally for individual patient anatomy when required.
Solution Approach 2:
The patent changes parameters dynamically by starting with dose calculation based on recording parameters, then adjusting the dose parameter using water equivalent diameter when patient-specific accuracy is needed. This parameter change approach allows the system to adapt between standardized and customized calculations based on clinical requirements, maintaining both productivity and precision.
4Measurement precision
If axial slice images are used for dose calculation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal dose calculation method that works across different CT device manufacturers and types by using standardized recording parameters and water equivalent diameter concepts. The method can universally process data from various devices without requiring device-specific calibration or complex device-integrated calculations, reducing overall system complexity while maintaining patient-specific accuracy.
Data Source
AI summary
In a method, a topogram of an examination volume is received via an interface. A water equivalent diameter (abbreviated to WED) of a slice plane of the examination volume is then determined, via a computer unit, based on the topogram. Thereafter, via the computer unit, a noise level is determined based on the WED, the noise level being an upper threshold value for noise of a CT image dataset. Finally, via the computer unit, a reference dose parameter is determined, based on the noise level determined and the WED, the reference dose parameter corresponding to a first x ray dose, absorbable in the slice plane during a recording of a first CT image dataset of the examination volume upon noise of the first CT image dataset corresponding to the noise level determined.