How do I convert TVT to HVT (or the other way around)?

This short article assumes that you know what 10th Value thickness (TVT) or 1/2 value thickness (HVT) mean. Note that these terms are also known as TVL and HVL respectively. They are used in simple gamma and x-ray shielding calculations. A fuller explanation of their use can be found in our glossary: 10th Value Thickness (TVT). Simply stated they mean:

• TVT - the thickness of a radiation shielding material that will reduce radiation (gamma / x-ray) dose or dose rate to 1/10th of the pre-shielded value.
• HVT - the thickness of a radiation shielding material that will reduce radiation (gamma / x-ray) dose or dose rate to 1/2 of the pre-shielded value.

Conversion

1TVT = 3.32HVT

1 HVT = 0.301 TVT

It is best to look up the actual values from reliable resources (or ask a Radiation Protection Adviser), but if you know one this will reliably give you the other.