A medical radioisotope source has an activity of $15\text{ millicuries } (\text{mCi})$. What is this activity in mega-becquerels ($\text{MBq}$)? (Given: $1\text{ Curie } (\text{Ci}) = 3.7 \times 10^{10}\text{ Becquerels } (\text{Bq})$).