How many HVL make up one TVL?

One TVL, or through-valley layer, is defined as the thickness of a material that reduces the intensity of radiation to one-tenth of its original value. This measurement is typically expressed in terms of half-value layers (HVL), which are the thicknesses of a given material that reduce the intensity of radiation by half.

To understand the relationship between HVL and TVL, it is important to know that each HVL reduces the radiation intensity by 50%. When you apply the concept of HVL repeatedly, you can reach a TVL through a series of reductions. Specifically, if you take the intensity of radiation and reduce it by half (one HVL), it is reduced to 0.5 times its original value. If you then reduce that result by half again (two HVLs), you have 0.25 of the original intensity. Continuing this pattern, you can observe that with three HVLs, you reach 0.125 of the original intensity, which means you have effectively reduced the intensity to approximately one-tenth (or 10%) of its original value. Thus, it requires three HVLs to reach one TVL.

This relationship is crucial in radiation therapy and medical dosimetry, as it provides a