Tool: Calculation of the K1 Factor for Measurements in Open Geometry
The evaluation model according to Filß takes into account the attenuation of radiation in the active matrix through the correction factor K1. The following tool allows the calculation of the K1 factor for various scenarios, such as different filling degrees and/or linear attenuation coefficients of the active matrix.
A detailed discussion can be found in the section Tools: Influence of the K1 factor.
Information on using the tool can be found at the end of the page.
Usage
The tool is used to calculate the K1 factor, which is incorporated into the evaluation model of a measurement in open geometry according to Filß. Additionally, it allows for better estimation of possible uncertainties by varying parameters.
Note: it is assumed that a cylindrical collimator is used.
The tool is divided into four sections.
Section 1: 2D Visualization of Path Lengths Depending on Angles
Depending on the chosen parameters (see Section 3), different values for the K1 values result depending on the respective azimuthal and elevation angles (φ, θ). Their distribution is shown in false color coding.
Especially in the edge areas of the active matrix, there often are significant deviations compared to the central areas.
Section 2: Visualization of (Measurement) Geometry
Based on the chosen parameters (see Section 3), the measurement geometry is schematically represented in top and side views. The area of the active matrix contributing to the detector signal is represented as a gray cone (triangles).
Section 3: Settings - Input of Parameters
In this section, parameters can be entered within specified limits. An immediate calculation of the K1 values and updates of the visualizations occur. The parameter res allows the accuracy of the calculation to be adjusted.
Information about the individual parameters can be obtained through tooltips that open when hovering over the respective parameters.
The calculated K1 value is displayed. The calculation was made by averaging the calculated K1(φ, θ) values for the discretized azimuthal and elevation angles (φ, θ). The resolution is set by the parameter res .
For comparison, the K1 value for a simplified determination K1 = K1(φ=0, θ=0) = exp(-μ⋅2⋅r) and its deviation from the average value are provided.
Note:
The value of the simplified determination is often also used for evaluations of measurements in collimated geometry since the variation of K1(φ, θ) within the opening angle of the collimator is generally negligible.
