This could lead to serious problems that occur if clonidine is stopped suddenly. Previous versions of the prescribing information for clonidine tablets and patches stated that the medication was approved for use in children as young as 12 years old. The current prescribing information states that these medications are not approved for use in children.
Therefore whereas a dental x-ray room may require a. nominal shielding of about 1.5mm lead for the direct beam and. about 0.7mm lead for the scattered field, a diagnostic x-ray. room may require a nominal shielding of about 3mm and 1.5mm. for the direct beam and scattered field respectively.
So you know that there are 3 kind of radiation, alpha, beta and gamma. Alpha can be stopped by a piece of paper. Beta by a few cm thick material but gamma has a high penetrating power and can travel a long distance in normal media. Hence a high density lead shield is used primarily for stopping gamma rays. High density means more interactions and hence quicker attenuation of gamma rays.