Eye Plaque Description
The dimensions of the COMS 10 mm eye plaque are available here (given in the TG129 report 1, 2). This plaque has indentations for 5 seeds within Silastic insert (seed coordinates here) in the Modulay backing, as shown in the above figures (generated using egs_view). The 3D dose distributions for the plaque containing 125I (6711), 103Pd (200), and 131Cs (CS-1 Rev2) (Ref. 3) are provided here (normalized per unit seed air kerma strength):
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HOMO (5 seeds modelled under TG43 conditions) and HETERO (fully-loaded eye plaque in water) for 103Pd: Zipped archive
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HOMO (5 seeds modelled under TG43 conditions) and HETERO (fully-loaded eye plaque in water) for 125I: Zipped archive
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HOMO (5 seeds modelled under TG43 conditions) and HETERO (fully-loaded eye plaque in water) for 131Cs: Zipped archive
Central axis depth dose curve
Doses along the plaque's central z-axis (CAX) for HOMO and HETERO scenarios are presented here for three radionuclides and compared with published BrachyDose 1, 4 and MCNP 5 results. Overall, HETERO doses are lower than the HOMO doses, due to the attenuation and scattering in the plaque backing and insert. For instance, HETERO/HOMO dose ratio at 0.5 cm on the CAX is 0.81, 0.88, and 0.90, for 103Pd, 125I, and 131Cs, respectively. The mean (range) percentage difference of HOMO doses along the CAX between egs_brachy and BrachyDose were 0.38% (-0.02%, 0.55%) for 103Pd, and -0.38% (-0.61%, -0.21%) for 125I, respectively. The corresponding values between egs_brachy and MCNP were 2.8% (0.32%, 4.6%) for 103Pd, 0.13% (-0.68%, 0.77%) for 125I, and 1.7% (1.2%, 2.4%) for 131Cs, respectively. The mean (range) percentage difference of HETERO doses along the CAX between egs_brachy and BrachyDose were -0.05% (-0.38, 0.13%) for 103Pd, and 0.63% (0.40%, 1.3%) for 125I, respectively. The corresponding values between egs_brachy and MCNP were 2.2% (-0.66%,3.7%) for 103Pd, -0.36% (-1.4%, 0.65%) for 125I, and 1.2% (0.83%, 1.6%) for 131Cs, respectively. It is worth noting that statistical uncertainties for egs_brachy, BrachyDose 4, and MCNP 5 are less than 0.20%, 1.0%, and 2.0%, respectively.
Transverse dose profile
Transverse dose profiles (along x and y axes) at depths of z = 0.5 cm and z = 1 cm are shown for three radionuclides. These dose profiles compared to available BrachyDose results from the previous database are in good agreement (< 1.3%).
103Pd, x view, z =0.5 and 1 cm |
103Pd, y view, z =0.5 and 1 cm |
125I, x view, z =0.5 and 1 cm |
125I, y view, z =0.5 and 1 cm |
131Cs, x view, z =0.5 and 1 cm |
131Cs, y view, z =0.5 and 1 cm |
-3371, 2008