Collimator Alignment in Photon Counting Radiography
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Solution Overview
Problem
Existing radiographic imaging apparatuses with photon counting type detectors require extensive man-hours for collimator alignment due to the need to acquire outputs from multiple radiation source positions, leading to inefficiencies and potential artifacts in tomographic images.
Innovation Solution
A radiographic imaging apparatus that aligns the collimator with the detecting element in a direction orthogonal to the radiation source, using output signals from adjacent detecting elements to ensure alignment within a predetermined ratio or difference range, allowing for fixed radiation source positioning and reduced alignment time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If outputs are acquired at two ray source positions for alignment, then alignment accuracy is improved, but man-hour and time consumption increase
Solution Approach 1:
The patent applies partial action by using only one ray source position for alignment instead of two, combined with selecting specific detecting elements (those adjacent to collimator walls) to achieve sufficient alignment accuracy without the full procedure requiring multiple positions. This reduces the alignment process from requiring two complete data acquisition cycles to one, directly reducing man-hour while maintaining acceptable alignment precision.
2Productivity
If alignment is performed with fixed radiation source position, then productivity is improved, but alignment precision may deteriorate
Solution Approach 1:
The patent introduces an intermediary approach by using output signals from specific detecting elements (those adjacent to collimator walls) as mediators to achieve alignment. Instead of relying on multiple radiation source positions, the method uses the differential signals from wall-adjacent detecting elements as an intermediary mechanism to determine alignment state, enabling single-position alignment while maintaining precision.
3Device complexity
If collimator alignment is not accurate, then device complexity is reduced, but image quality deteriorates due to artifacts
Solution Approach 1:
The patent replaces a mechanical/multistep alignment system with a signal-processing-based system. Instead of requiring complex mechanical positioning and multiple measurement positions, the invention uses electronic signal acquisition from detecting elements and computational processing of output signals to achieve alignment. This substitution simplifies the alignment procedure while ensuring sufficient precision to prevent image artifacts.
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 enables accurate and efficient alignment of the collimator with the detecting element, reducing man-hour requirements and minimizing artifacts in tomographic images by maintaining alignment precision while fixing the radiation source position.
Implementation Method 1
a radiation source that irradiates a subject with radioactive rays
Implementation Method 2
a slit-type or grid-type collimator which is made of a heavy metal such as tungsten, molybdenum, tantalum, and so forth is disposed between a subject and a detecting element in order to suppress incidence of scattered rays
Implementation Method 3
the photon counting type detector which adopts a photon counting system to individually count the number of photons in a radioactive ray which is incident upon each detecting element which is formed in a semiconductor layer
Data Source
AI summary
There is provided a radiographic imaging apparatus capable of alignment of a detector with a collimator with a position of a radiation source fixed. The radiographic imaging apparatus includes the radiation source which irradiates a subject with radioactive rays, a plurality of detecting elements which detect photons in the radioactive rays, and a collimator which is disposed between the radiation source and the detecting elements and has a plurality of walls which form a plurality of passing holes that the radioactive rays pass. The detecting element and the collimator are aligned with each other in a direction which is orthogonal to a direction that the subject is irradiated with the radioactive rays such that a ratio or a difference between output signals from the detecting elements which are mutually adjacent with the wall being interposed falls within a predetermined range.