Value of total filtration for 70 kVp is:

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 Pharoah's Oral Radiology Principles and Interpretation 7th edition page no 10,11