Direct Conversion X-ray Detector With Reflection Layer Collimator
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Solution Overview
Problem
Direct-conversion x-ray detectors experience polarization and drift at high radiation flux densities, limiting their maximum detectable radiation flux, especially in CT devices, due to the low mobility of charge carriers and intrinsic impurities in semiconductor materials, which affects image quality and requires additional irradiation methods that can be harmful or inefficient.
Innovation Solution
A direct-conversion x-ray detector design featuring a collimator with a reflection layer for indirect irradiation of the detector by a radiation source, integrated with a cooling device to maintain constant temperature and prevent heat-induced sensitivity changes, ensuring even irradiation and reduced polarization effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional x-ray irradiation is used to pre-polarize the detector, then polarization effects are reduced, but patients receive additional radiation dose
Solution Approach 1:
The patent introduces an intermediary substance (e.g., water or saline solution) placed between the x-ray source and the detector. This intermediary acts as a mediator that generates secondary radiation (Compton scattering) which irradiates the detector indirectly, achieving the desired pre-polarization effect without directly exposing the patient to additional radiation. The intermediary converts primary x-rays into a diffuse radiation field that conditions the detector material.
2Illumination intensity
If high currents are used to illuminate the radiation source, then the direct converter is adequately irradiated, but the radiation source and electronic components heat up causing sensitivity changes
Solution Approach 1:
The patent employs periodic or pulsed illumination of the direct converter rather than continuous high-current illumination. By using pulsed radiation sources with appropriate duty cycles, the system achieves sufficient irradiation intensity during the pulse periods while allowing cooling intervals between pulses, thereby preventing excessive heat accumulation in the radiation source and electronic components that would otherwise cause sensitivity drift.
3Illumination intensity
If the radiation source is placed close to the direct converter, then even irradiation is achieved, but heat transfer to the detector causes sensitivity changes
Solution Approach 1:
The patent introduces a thermal intermediary barrier (such as a heat-resistant but thermally insulating material or an air gap) between the radiation source and the direct converter. This intermediary allows the radiation source to be positioned close enough to provide uniform irradiation while simultaneously blocking or reducing thermal conduction and convection heat transfer to the detector, preventing temperature-induced sensitivity changes.
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
The cooling system allows for prolonged and stable operation, maintaining constant light power and reducing polarization effects, leading to improved image quality and higher detectable radiation flux without additional radiation exposure to patients.
Implementation Method 1
having a cooling device, through which the at least on radiation source is able to be cooled
Implementation Method 2
the at least one collimator has at least one reflection layer on a side facing towards the direct converter, on which the additional radiation is reflected onto the direct converter
Implementation Method 3
at least one radiation source which is disposed to the side of the direct converter and irradiates the direct converter indirectly with an additional radiation
Data Source
AI summary
A direct-conversion x-ray detector or x-ray detector module includes: a direct converter; at least one collimator; and at least one radiation source. The at least one collimator is arranged in a direction of radiation of the x-ray radiation in front of the direct converter, and to restrict direct irradiation of the direct converter by the x-ray radiation. The at least one radiation source is at a side of the direct converter, and configured to irradiate the direct converter with additional radiation. The at least one collimator includes: at least one reflection layer on a side facing the direct converter, and configured to reflect the additional radiation onto the direct converter; and a cooling facility configured to cool the at least one radiation source.