TCID50 is an endpoint dilution assay quantifying the amount of virus required to kill 50% of infected hosts, in many cases cells. So, it depends not only on the cell-line/cells you are using but also on the virus. Viruses may produce a lot more DNA/RNA than actual viral particles, thus qPCR values and TCID50 values may differ widely, esp if one uses different cell to calculate TCID50 values. So, if you are "lucky", it may tell you something, but not for all viruses, esp those with only small cpe effects.

thanks for reply, the thing I am struggling with is that, what amount of virus or dose we are talking about while we are testing unknown titer sample(unknown quanitity of virus)?

:-) Good question. These days, everyone is using qPCR to detect viral DNA/RNA in samples, so I would start initially with that. However, if you want to be precise regarding an infectious dose (i.e. for an in vitro or in vivo experiment), the most accepted value is TCID50. Does this make sense?

thanks for help, I got what i need thank you.