<prompt> Value of total filtration for 70 kVp is2.1 mm2.3 mm1.5 mm2.5 mm  <response>: Total filtration is the sum of the inherent and added filtration. 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.Oral Radiology, Principles and Interpretation Stuart C. White, Michael J. Pharoah - 7th ed - pg - 10,11 