Is Incremental Back up possible with Sector By Sector Back Up Method?

Hi, I have 64bit Windows 7 Ultimate running on my laptop with BitlLocker enabled on my data disk. (Not C drive System Disk).
I have enabled BitLocker on this drive and performed Sector By Sector Back Up per advice I gathered on the forum. Since it is not the system disk, I have performed initial Sector By Sector Back Up within Windows 7 enviroment while BitLocker protected disk is open (but not turned off).

My question is: Do I always have to perform the FULL BACK UP everytime I want to update the back up image? Or can I perform incremental back up while choosing sector by sector back up option?

Thanks for your help in advance.