<prompt> Value of total filtration for 70 kVp is:2.1 mm2.3 mm1.5 mm2.5 mm  <response>: Governmental regulations require the total filtration in the path of a dental X-ray beam to be equal to the equivalent of 1.5 mm of aluminum for a machine operating at up to 70 kVp and 2.5 mm of aluminum for machines operating at higher voltages.Reference: White and Pharoahs Oral Radiology Principles and Interpretation 7th edition page no 10,11 