Roentgen (unit) absorbed dose in a wide range of matter. When measuring absorbed dose in a human due to external exposure, the SI unit the gray, or the related non-SI rad are used. From these can be developed the dose equivalents to consider biological effects from differing radiation types and target materials. These are equivalent dose, and effective dose for which the SI unit sievert or the non-SI rem are used. The following table shows radiation quantities in SI and non-SI units: Roentgen (unit) The roentgen or röntgen () (symbol R) is a legacy unit of measurement for the exposure of X-rays
Roentgen (unit) the SI. The US NIST clarified in 1998 that it was providing its own interpretations of the SI system, whereby it accepted the roentgen for use in the US with the SI, while recognizing that the CIPM did not. By then, the limitation to x and γ radiation had been dropped. NIST recommends defining the roentgen in every document where this unit is used. The continued use of the roentgen is strongly discouraged by the NIST. Whilst a convenient quantity to measure with an air ion chamber, the rontgen had the disadvantage that it was not a direct measure of