Exporting to a XML, need the Field Source not Field Name

Hello, I have a report based on a dataset.  For example the query for dataset is

Select first_Name as "First Name",

last_name as "Last Name",

age,

phone_No as "Phone Number"

From myTable

In SSRS under property of Dataset > Fields we have the Field Name and Field Source

In this case the Field Name would be  first_Name, last_name, age, phone_No and the Field Source would be First Name, Last Name, age, Phone Number

when report get exported to a xml file only the field name goes cross.  Then when the xml gets imported into Excel for example, it shows the Field Name.  How can we reference to the Field Source?

Thanks