Filter Dimension by Parameter in SSRS DataSet using MDX

I have a Tabular Model in SSAS.

There are two tables:

1. DimQuestions (QuestionKey, QuestionDesctiption, QuestionGroup)
2. DimQuestionGroup (QuestionGroupKey, QuestionGroup)
3. FactResults (...)

I also added another table:

• Security (Username, QuestionGroup)

I am creating a DataSet in SSRS and there I want to select only the QuestionKeys(from DimQuestion) where a specific username has access to according to the tableSecurity. One username may have access to multiple groups, and a group may be available to multiple usernames.

Is there a best practice to achieve this? How to achieve this using MDX?