Mohn Doss, Medical Physicist in Diagnostic Imaging. The ALARA concept, As Low As Reasonably Achievable is base on the linear no-threshold (LNT) model assumption and / or low--dose radiation cancer concerns. Do mutations increase linearly with radiation dose? When radiation dose increases, at low doses, mutations decrease. Cancers do not increase linearly with mutations. There are many more reasons to conclude: Mutation model of cancer is not valid. See for example slide 6 / 13.