Transversal CT slices at two locations, where the dose difference profiles behind bones were investigated; (a) illustrates the location at 2.5-cm-thick femur position and (b) at 5.5-cm-thick femoral head position. The upper edge of the image is set at the gelatine surface, and the cubic 5-mm ICs of the detector are shown at the bottom of the image.
The dose difference profiles [Δ D by Eq. (1) ] behind bones (radiation traversed through bones) compared to those obtained through gelatine only at 6 MV. (a) and (b) show the profiles behind the femur at two positions, (c) behind the metaphysis, and (d) behind the femoral head and greater trochanter. In the diagrams the half centimeter wide bars represent measurement results, while the calculation results in the standard CT image are represented with the solid lines (XiO® superposition s.p.) and solid dots (Monaco® MC). In the upper diagrams there are represented calculation results in the bulk density pseudo-CT image with dashed line (s.p.) and open squares (MC). In the lower diagrams there are illustrated calculation results in the conversion-based pseudo-CT image with dashed line (s.p.) and open triangles (MC).
The calculated dose point deviations in the bulk density [and in the conversion-based] pseudo-CT images compared to those in the CT image.
The average (and maximum) differences between the dose calculations in the standard CT image and the measured doses at different ionization chamber positions.
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