CT Calcium Scoring Dose Adaptation by BMI
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Solution Overview
Problem
Repeated calcium scoring examinations using CT scanners expose patients to substantial cumulative ionizing radiation, with existing methods either irradiating patients excessively or failing to achieve optimal noise levels, leading to inaccurate calcium detection.
Innovation Solution
A diagnostic imaging system that adjusts the x-ray tube current (mAs) based on a patient's body mass index (BMI) squared to minimize radiation dose while maintaining noise levels below a preselected threshold, ensuring accurate calcium scoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fixed low dose (e.g., 40 mAs) is used for calcium scoring, then radiation dose is reduced, but noise level increases causing inaccurate calcium detection
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed dose protocol to a dynamic dose adjustment system. The tube current (mAs) is automatically adjusted based on the patient's lateral thickness measured in real-time during the scan, allowing the radiation dose to adapt to each patient's body size while maintaining consistent noise levels across different patient populations
Solution Approach 2:
The patent changes the parameter of tube current (mAs) based on patient lateral thickness. By measuring the actual thickness of the patient's body and adjusting the mAs accordingly, the system optimizes the radiation dose to achieve the target noise level of 20 HU for each individual patient, rather than using a one-size-fits-all fixed dose approach
2Measurement precision
If patients are divided into three size categories with fixed recommended doses, then noise levels are improved for smaller patients, but larger patients still receive insufficient dose and smaller patients receive excessive radiation
Solution Approach 1:
The patent segments the patient population not by arbitrary size categories, but by actual measured lateral thickness values. This continuous segmentation approach divides patients into groups based on their specific thickness measurements, allowing for more precise dose tailoring compared to broad categorical approaches
Solution Approach 2:
The patent applies local quality by tailoring the radiation dose to each patient's specific lateral thickness. Instead of applying a uniform dose or broad category-based dose, the system adjusts the mAs locally for each patient based on their individual body dimensions, ensuring optimal noise levels and minimal radiation exposure for each specific case
3Measurement precision
If tube current (mAs) is increased to reduce noise, then noise level improves, but radiation dose increases exposing patients to unnecessary radiation
Solution Approach 1:
The patent implements feedback by measuring the patient's lateral thickness during the scan and using this information to adjust the tube current (mAs). The system continuously monitors the actual patient dimensions and adjusts the radiation dose in real-time to achieve the target noise level, preventing both under-dosing and over-dosing scenarios
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 effectively reduces radiation exposure while maintaining consistent noise levels, ensuring accurate calcium detection and scoring over time, thereby minimizing the risk of radiation-related harm.
Implementation Method 1
An x-ray tube irradiates a patient with an x-ray beam
Data Source
AI summary
A weight (22) and height (24) of a patient who is to undergo a calcium screening examination in an x-ray diagnostic scanner (10) is used to calculate an appropriate x-ray dose in terms of tube current (mAs) for the calcium screening examination in accordance with the formula: mAs=c(BMI)2, where BMI is a patient's body mass index defined as: BMI=patent weight_(patient height)2.and C is a constant selected in accordance with a target required noise. In this manner, patients can be scanned with a minimum dose necessary to achieve the target noise, e.g., 20 HU. The images can be compared with earlier (and subsequent) images that have the same target noise.