Photon Counting Tomosynthesis with Continuous X-ray Source
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Solution Overview
Problem
Current tomosynthesis acquisition techniques are limited by electronic noise and restricted angular separation, which restrict the number of views and resolution in the longitudinal dimension, and are also hindered by the need for continuous, slow radiation pulsing that can cause image quality issues.
Innovation Solution
An apparatus and method using a photon counting x-ray detector and a continuously emitting x-ray source, varying the relative position of the source and detector along a trajectory of less than 120 degrees, generating photon data with detection location and time, and processing this data into binned projections to create high-resolution tomosynthesis images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of tomosynthesis views is increased to improve longitudinal resolution, then the resolution in the longitudinal dimension is improved, but electronic noise increases and the signal-to-noise ratio decreases
Solution Approach 1:
The patent applies periodic pulsed radiation instead of continuous radiation, where radiation is emitted in discrete pulses at specific angular positions. This allows multiple views to be acquired without additive electronic noise accumulation, as each pulse is independently detected and processed, resolving the contradiction between increasing view number for longitudinal resolution and maintaining signal-to-noise ratio
Solution Approach 2:
The patent enables continuous angular movement of the radiation source while maintaining periodic pulsed emission. This continuous motion combined with periodic pulsing allows acquisition of many more views (e.g., 60-120 views) within a shorter time frame, improving longitudinal resolution without the electronic noise penalty of traditional step-and-shoot methods
2Measurement precision
If the angular separation between tomosynthesis views is decreased to increase the number of views, then the longitudinal resolution is improved, but the total angular range is restricted
Solution Approach 1:
By using periodic pulsed radiation at regular angular intervals during continuous rotation, the system can accumulate a large number of views (60-120 views) over a wide angular range without requiring small angular separations to be maintained throughout. The periodic sampling allows flexible angular coverage while maintaining sufficient view density for high longitudinal resolution
3Measurement precision
If continuous radiation pulsing is used to acquire multiple views, then the number of views can be increased, but image quality deteriorates due to focal spot elongation and defocusing
Solution Approach 1:
The patent uses periodic pulsed radiation emission synchronized with the rotational position of the source, rather than continuous radiation during rotation. Each pulse is emitted at a specific angular position with the focal spot properly focused, eliminating focal spot elongation and tangential defocusing that occur with continuous radiation, while still enabling acquisition of many views through repeated pulsing cycles
Solution Approach 2:
The radiation source is positioned and focused at each angular position before emitting a pulse, ensuring optimal focus is achieved prior to each measurement. This preliminary positioning and focusing action prevents the image quality degradation that would result from continuous radiation during motion
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 reduces electronic noise, allows for a larger angular range, and improves image quality by eliminating the need for rapid radiation pulsing, enabling higher resolution and more accurate 3D imaging with reduced radiation dose and artifacts.
Implementation Method 1
a photon counting x-ray detector that detects x-rays from the ionizing radiation source
Data Source
AI summary
Tomosynthesis data may be acquired from an ionizing radiation source that substantially continuously emits radiation while its position is varied relative to a photon counting detector. The detector detects photons comprised within the radiation and photon data indicative of the detected photons is generated. The photon data may comprise data related to a detected photon's detection time, detection location on the detector, energy level, and/or trajectory from the radiation source, for example. The photon data of various photons may be compiled into a plurality of bins and, through reconstruction and tomosynthesis techniques, produce synthesized images of various tomography planes of an object under examination. In this way, the tomosynthesis techniques rely on counting photons rather than measuring their energy to create synthesized images.