Tomosynthesis Irradiation Field Limiter for Radiation Leakage Control
Solution Overview
Problem
Tomosynthesis imaging apparatuses face issues with unnecessary exposure due to radiation leakage from irradiation openings corresponding to adjacent radiation tubes, which affects the signal-noise ratio and exposure levels during imaging.
Innovation Solution
A tomosynthesis imaging apparatus with a radiation source comprising three or more radiation tubes and an irradiation field limiter featuring first and second opening portions arranged along a straight line connecting the radiation tubes' focuses, where the first rotating member is rotated to different positions to optimize the irradiation field, preventing radiation leakage and reducing exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an irradiation field limiter having irradiation openings formed so as to correspond to each of a plurality of radiation tubes is applied, then the irradiation field can be defined for each radiation tube, but radiation leaks from the irradiation openings corresponding to adjacent radiation tubes causing unnecessary exposure
Solution Approach 1:
The patent applies the dynamics principle by making the irradiation field limiter rotatable about an axis parallel to the straight line connecting the focuses of the radiation tubes. The limiter can rotate between a first position where opening portions face specific radiation tubes and a second position where they face adjacent radiation tubes, enabling dynamic adjustment of the irradiation field to prevent radiation leakage while maintaining precise field definition.
Solution Approach 2:
The irradiation field limiter is segmented into multiple opening portions, each corresponding to a specific radiation tube. This segmentation allows each opening portion to independently control the irradiation field for its associated radiation tube, preventing radiation from leaking into adjacent tubes' fields while maintaining precise definition for each tube.
2Measurement precision
If three or more radiation tubes are used with adjacent tubes brought close to each other, then the signal-noise ratio of the tomographic image is improved, but radiation leakage from adjacent irradiation openings causes unnecessary exposure
Solution Approach 1:
The rotatable irradiation field limiter dynamically adjusts the irradiation field configuration when radiation tubes are brought close together. By rotating to appropriate positions, the limiter ensures that opening portions face only the intended radiation tubes, preventing cross-contamination of radiation fields while maintaining the high signal-noise ratio achieved through close tube spacing.
Solution Approach 2:
The irradiation field limiter acts as an intermediary between the radiation tubes and the object being imaged. It mediates the radiation flow by selectively allowing radiation from specific tubes to pass through corresponding opening portions while blocking radiation from adjacent tubes, thus preventing unnecessary exposure while maintaining the benefits of close tube spacing for improved signal-noise ratio.
3Adaptability or versatility
If the irradiation field limiter is rotated to different positions, then the irradiation field can be optimized for different radiation tubes, but the device complexity increases
Solution Approach 1:
The patent implements a rotatable irradiation field limiter that can be positioned at different angular orientations to optimize the irradiation field for different radiation tubes. This dynamic positioning capability allows the system to adapt to various imaging configurations while using a relatively simple rotational mechanism rather than complex multiple limiters.
Solution Approach 2:
The single rotatable irradiation field limiter serves multiple functions by being able to face different radiation tubes at different positions. Instead of requiring a separate fixed limiter for each radiation tube, this universal component can be rotated to provide the appropriate irradiation field definition for any active radiation tube, reducing overall device complexity.
Data Source
AI summary
Fifteen radiation tubes are arranged in a radiation source of the mammography apparatus. An irradiation field limiter has a plurality of first irradiation opening portions which are provided in an X direction and each of which is configured by a pair of a first opening and a second opening facing each other in an irradiation direction of radiation and defines an irradiation field of the radiation. The irradiation field limiter includes a first rotating member that is rotated to a first rotation position and a second rotation position about a rotating shaft parallel to the X direction. At the first rotation position and the second rotation position, the first irradiation opening portions which are arranged at an interval of one radiation tube face the radiation tubes in the irradiation direction. The first irradiation opening portions deviate from each other in the X direction. Among 15 radiation tubes, at least some of second radiation tubes, which are other than first radiation tubes facing the first irradiation opening portions at the first rotation position and do not face the first irradiation opening portions, face the first irradiation opening portions at the second rotation position.