X-ray Detector Self-Synchronization via Parasitic Capacitance
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Solution Overview
Problem
Current photosensitive devices in medical radiology require synchronization between the X-ray source and the detector to ensure accurate image capture, which necessitates structural modifications and connection means, limiting mobility and reliability, especially with wireless links.
Innovation Solution
A method that allows autonomous synchronization of photosensitive devices by detecting photon arrival without additional sensors or read pulses, using parasitic capacitance in transistors to determine potential differences and trigger reading phases, enabling efficient photon detection without connection to the radiation source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronization connection means are added between base station and cassette, then image capture accuracy is improved, but device complexity and mobility are worsened
Solution Approach 1:
The solid-state detector performs self-synchronization by autonomously detecting the start and end of X-ray emission through monitoring potential variations on its own column conductors. This eliminates the need for external synchronization connections between the base station and cassette, as the detector independently determines when to activate its acquisition window based on real-time radiation detection.
Solution Approach 2:
The patent replaces mechanical/electrical synchronization connections with an electromagnetic field-based detection system. By monitoring potential variations on column conductors that occur naturally during X-ray exposure, the system substitutes physical connection means with a field-based sensing approach that provides both synchronization and detection functions.
2Reliability
If wired connection means are used for synchronization, then synchronization reliability is improved, but mobility is worsened
Solution Approach 1:
The detector autonomously performs synchronization detection without requiring external connection means, enabling the cassette to be freely mobile while maintaining reliable synchronization. The system monitors potential variations on its own column conductors to detect X-ray emission events, eliminating the trade-off between connection reliability and mobility.
3Speed
If reading phase is performed during X-ray exposure, then detection speed is improved, but image quality is worsened
Solution Approach 1:
The system performs preliminary detection of X-ray emission start and end times by monitoring potential variations on column conductors before the actual image acquisition. This allows the detector to open its acquisition window in advance and close it precisely when exposure ends, ensuring complete capture of the radiation event without degrading image quality through premature or extended reading.
Solution Approach 2:
The system uses feedback from potential variation monitoring on column conductors to dynamically control the acquisition window timing. The detected potential changes provide real-time feedback about X-ray emission status, allowing the detector to adjust its reading phase timing to perfectly match the exposure window, thereby maintaining both speed and image 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
Enables seamless replacement of radiological film cassettes with solid-state detectors in X-ray systems without structural modifications, maintaining image quality and improving mobility and reliability by eliminating the need for connection means.
Implementation Method 1
Each photosensitive point is generally made up of at least one photosensitive element such as a diode... the photosensitive elements are exposed to radiation which they convert into electrical charges
Implementation Method 2
The invention is based on an intrinsic property of transistors, namely the presence of a parasitic coupling capacitance which naturally exists in the off state between the drain and the source... This parasitic coupling capacitance is relatively low, for example of the order of 10 femtofarad
Data Source
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AI summary
The invention relates to a method for controlling a light-sensitive device, for example, a digital X-ray detector including an array of light-sensitive points. The light-sensitive device includes a column conductor, line conductors, and light-sensitive points. Each light-sensitive point is connected between the column conductor and one of the line conductors, and includes a light-sensitive element capable of converting a photon flux into electrical charges, and a transistor capable of transferring the electrical charges to the column conductor based on the control of a signal received by the corresponding line conductor. The invention depends on the presence of a capacitor for cross-coupling between the drain and the source of each transistor in the off state. Said capacitor provides a potential variation to the column conductor upon receiving photons. The method according to the invention comprises steps (21, 22, 23, 24) for comparing the potential variation with a threshold, and a step (25) of reading the light-sensitive points is carried out in the event that the result of the comparison is positive.