You could definitely accomplish this with a parameter. I can't give you an exact solution without a sample packaged workbook to work with, but I can try to explain it so that you can work it out. First, you're going to want to right click your date field and select Create>Parameter and format the parameter as week numbers, then show the parameter control. Then, you'll want to create a calculated field based on that parameter that you can use as a filter. Again, I can't say for sure what the syntax will be, but it should be something along the lines of:
IF DATEPART('week', [Date])=DATEPART('week', [Date Parameter])
OR DATEPART('week', [Date])=DATEPART('week', [Date Parameter])-1
Then, just filter on the "YES" values and you should be good to go.