<prompt> A 26 year old male presented to the dental clinic with pain in the right lower back tooth region. On examination, it was evident that pericoronitis is present with 48. The inherent filtration of the machine used is 3 mm of Aluminium operating at 70 kVp. By the use of this machine, the surface exposure:Reduces to 20 of the exposure without filtrationReduces to 80 of the exposure without filtrationReduces to 30 of the exposure without filtrationIs not reduced at all  <response>: Filtration results in decreased patient exposure with no loss of radiographic information. When an X-ray beam is filtered with 3 mm of aluminum, the surface exposure is reduced to approximately 20 of the exposure with no filtration. Reference: ORAL RADIOLOGY PRINCIPLES AND INTERPRETATION,8th EDITION, Stuart C. White,Michael J. Pharoah 