Tomosynthesis Imaging With a Movable Irradiation Field Limiter
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Solution Overview
Problem
Existing tomosynthesis imaging apparatuses suffer from unnecessary exposure due to radiation leakage from irradiation openings corresponding to adjacent radiation tubes, which is not effectively addressed by current collimator designs.
Innovation Solution
The apparatus employs an irradiation field limiter with a plate-like member having through holes that can be moved along the arrangement direction of radiation tubes, adjusting the position of irradiation openings to prevent radiation leakage, using mechanisms such as displacement mechanisms, convex portions, and adjustable through holes to define the irradiation field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an irradiation field limiter with fixed irradiation openings corresponding to each radiation tube is used, then radiation leakage from adjacent tubes is prevented, but the device complexity increases and unnecessary exposure occurs when adjacent tubes are activated
Solution Approach 1:
The patent applies the dynamics principle by making the irradiation field limiter movable rather than fixed. The limiter can shift its position to align irradiation openings with different radiation tubes depending on which tube is active. This dynamic adjustment prevents radiation leakage from adjacent tubes while avoiding unnecessary exposure, without requiring a complex fixed structure for each possible tube position.
2Measurement precision
If three or more radiation tubes are arranged closely to improve SN ratio, then image quality improves, but radiation leakage from adjacent tubes causes unnecessary exposure
Solution Approach 1:
The movable irradiation field limiter dynamically adjusts its position to match the active radiation tube, enabling close arrangement of multiple radiation tubes to improve signal-noise ratio while preventing radiation leakage from adjacent tubes. The limiter shifts to align openings only with the currently active tube, blocking radiation from neighboring tubes and thus eliminating unnecessary exposure.
3Manufacturing precision
If irradiation openings are positioned for each radiation tube, then precise radiation delivery is achieved, but radiation leaks from adjacent tube openings causing unnecessary exposure
Solution Approach 1:
The patent resolves the contradiction between precise irradiation field definition and radiation leakage by implementing a movable irradiation field limiter. Instead of having fixed openings for each tube that cause leakage, the limiter dynamically repositions to align openings precisely with the active tube only, maintaining manufacturing precision while preventing adjacent tube leakage.
Data Source
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AI summary
Provided is a tomosynthesis imaging apparatus that can prevent unnecessary exposure. Fifteen radiation tubes are arranged in a radiation source of the mammography apparatus. An irradiation field limiter includes a plate-like member having a plurality of through holes that function as irradiation openings. Adjacent through holes are arranged at an interval of one radiation tube. In the plate-like member, the position of the through holes which are irradiation openings are moved to a first set position in a case in which radiation is emitted from first radiation tubes which are some of three or more radiation tubes and a second set position in a case in which the radiation is emitted from second radiation tubes different from the first radiation tubes among the three or more radiation tubes. Therefore, one through hole is shared by two radiation tubes.