Carrier attenuation correction should be included in dose calculations when the density or atomic composition of the seed carrier differs significantly from water. The COMS plaques use a Silastic silicone carrier. The Silastic material is about 40% Si by weight and has an effective Z of about 10.7 compared to 7.4 for water.
Important: Scatter and flourescence corrections are already included in the carrier factor for COMS plaques that use a silicone carrier because flourescence from the gold will be entirely absorbed in the silicone seed carrier and never reach the eye. Thus, for a COMS plaque that uses a silicone carrier, the carrier factor T(r,d,μ) should be enabled, and the scatter & flourescence factor B(r) should be disabled. For plaques that do not use a seed carrier (e.g. Eye Physics plaques) and for a COMS plaque that uses a gold insert instead of silicone, carrier corrections should be disabled, and the scatter & flourescence factor B(r) factor should be enabled.