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Definition of Tenth-value layer
Tenth-value layer or "TVL" means the thickness of a specified material that attenuates x-radiation or gamma radiation to an extent such that the air kerma rate, exposure rate, or absorbed dose rate is reduced to one-tenth of the value measured without the material at the same point.
Also question is, how is HVL calculated?
Determine the attenuation coefficient of a material. This can be found in a table of attenuation coefficient or from the manufacturer of the material. Divide 0.693 by the attenuation coefficient to determine the HVL. The half-value layer formula is HVL = = 0.693/μ.
Keeping this in view, why is half value layer important?
Half value layer. HVL is an important quality control test as it is used to measure whether or not there is sufficient filtration in the x-ray beam to remove low energy radiation, which can be damaging. It also helps to determine the type and thickness of shielding required in the facility.
Half-value layer (HVL) is the width of a material required to reduce the air kerma of an x-ray or gamma-ray to half its original value. This applies to narrow beam geometry only as broad-beam geometry will experience a large degree of scatter, which will underestimate the degree of attenuation. HVL = 0.693 / μ