Duplex Wire Image Quality Indicators (IQIs) are essential tools in non-destructive testing (NDT) radiography, to evaluate the resolution and contrast sensitivity of imaging system. Composed of two sets of high-density metal wires (platinum or gold) arranged in parallel or crossed configurations, indicators help determine the smallest detectable flaw by assessing image sharpness and unsharpness.
Duplex Wire Image Quality Indicators (IQIs) are specialized tools used in radiography and non-destructive testing (NDT) to evaluate the image quality and resolution of X-ray or gamma-ray imaging systems, particularly for inspecting welds, pipelines, and other critical structures.
Key Features of Duplex Wire IQIs:
Design:
Consists of two sets of wires (usually made of platinum or other high-density materials) arranged in a parallel or crossed pattern.
Each wire has a different thickness, allowing assessment of contrast sensitivity and spatial resolution.
Purpose:
Measures the smallest detectable defect (resolution capability) of an imaging system.
Evaluates contrast sensitivity (ability to distinguish between small differences in material density).
Helps ensure compliance with ASTM E747, ISO 19232, and other NDT standards.
How It Works:
Placed on or near the test object during radiography.
The resulting image shows whether the wires are clearly visible, indicating the system's resolution and contrast performance.
The smallest visible wire determines the Image Quality Indicator (IQI) sensitivity.
Common Standards:
ASTM E747 – Standard Practice for Design, Manufacture, and Material Grouping Classification of Wire IQIs.
ISO 19232-1 to -5 – Image quality indicators for radiographic testing.
EN 462-1 to -5 – European standards for wire IQIs.
Advantages of Duplex Wire IQIs Over Other Types (e.g., Hole-Type IQIs):
Better for assessing fine details in high-resolution imaging.
More sensitive to small changes in contrast.
Preferred for digital radiography (DR) and computed radiography (CR) applications.
Typical Applications:
Aerospace (inspecting turbine blades, welds).
Oil & Gas (pipeline weld inspection).
Automotive & Manufacturing (casting defect detection).