Tomosynthesis AEC Calibration Across Wide Projection Angles

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Solution Overview

Problem

Wide-angle tomosynthesis systems face challenges in accurately calculating automatic exposure control (AEC) dosage due to varying angles and heel effects, which affect detector count values and shift the center location of the breast projection, leading to inaccurate radiation dosage calculations.

Innovation Solution

The system generates reference detector count maps at each projection angle, using curve fitting to estimate values at intervening angles, and calculates AEC dosage by comparing scout image detector counts with reference maps, considering angle and heel effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If wide-angle tomosynthesis is performed with varying projection angles, then image coverage and diagnostic capability are improved, but radiation dosage calculation accuracy deteriorates due to heel effects and center location shifts

Engineering Contradiction:

Improveimage coverageVSAvoidradiation dosage calculation accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system performs preliminary actions by acquiring reference images at multiple known projection angles before the actual tomosynthesis scan. These reference images are used to pre-calculate correction factors for heel effects and center location shifts at each angle. During the actual scan, the system interpolates between these pre-calculated values to accurately determine radiation dosage without real-time recalibration

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes parameters by dynamically adjusting the projection angle throughout the tomosynthesis sweep. For each angle, the system calculates the corresponding heel effect magnitude and center location shift, then uses these angle-specific parameters to correct the radiation dosage calculation. This allows accurate dosage determination despite varying angles

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If conventional AEC methods are used with fixed calibration, then device operation is simple, but measurement precision deteriorates due to angle-dependent heel effects and projection center shifts

Engineering Contradiction:

Improvedevice operation simplicityVSAvoiddetector count value accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system performs self-service by automatically acquiring reference images, calculating correction factors, and applying angle-specific adjustments without requiring manual intervention. The processor autonomously determines the projection angle, selects appropriate correction factors, and calculates the accurate radiation dosage, maintaining ease of operation while improving precision

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If radiation dosage is increased to compensate for heel effects, then image quality in peripheral regions is improved, but patient radiation exposure increases

Engineering Contradiction:

Improveimage qualityVSAvoidpatient radiation exposure

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The system applies local quality by determining the specific projection angle and applying angle-appropriate correction factors only to the regions affected by heel effects at that angle. Rather than uniformly increasing radiation across the entire breast, the system selectively adjusts dosage for peripheral regions experiencing heel effects, maintaining image quality while minimizing overall patient exposure

Inventive Principle:

Principle #3Local quality

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 method ensures accurate radiation dosage calculation for wide-angle tomosynthesis, balancing image quality and patient exposure, without the need for equipment re-alignment, thus improving diagnostic image clarity.

Implementation Method 1

acquire a scout image of a patient's breast at a first projection angle by emitting a scout x-ray dosage towards the patient's breast

Methodology Applied

Scientific EffectX-ray emission: X-Ray

Data Source

PatentUS20260020827A1Wide angle automatic exposure control in tomosynthesis

Publication Date: 2026.01.22 HOLOGIC INC

AI summary

The present application discloses a system and method to calculate the automatic exposure control (AEC) calibrated dosage for tomosynthesis sweeps. For example, reference images may be acquired, and corresponding reference detector count maps may be generated and stored for a plurality of projection angles using the tomosynthesis imaging system. The tomosynthesis imaging system may then acquire a scout image using a scout dosage, identify the densest region within the scout image, and calculated the average detector count values associated with the densest region. The AEC calibrated dosage can be calculated based on a ratio of the average reference detector count values, corresponding to the detector count values of pixels with a corresponding densest region of the reference image, and the calculated average detector count values.